Polypeptide YY (PYY) and pancreatic polypeptide (PP) in rectal carcinoids. An immunocytochemical study

Neuropeptide Y Peptide Family and Cancer: Antitumor Therapeutic Strategies

Currently available data on the involvement of neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) and their receptors (YRs) in cancer are updated. The structure and dynamics of YRs and their intracellular signaling pathways are also studied. The roles played by these peptides in 22 different cancer types are reviewed (e.g., breast cancer, colorectal cancer, Ewing sarcoma, liver cancer, melanoma, neuroblastoma, pancreatic cancer, pheochromocytoma, and prostate cancer). YRs could be used as cancer diagnostic markers and therapeutic targets. A high Y1R expression has been correlated with lymph node metastasis, advanced stages, and perineural invasion; an increased Y5R expression with survival and tumor growth; and a high serum NPY level with relapse, metastasis, and poor survival. YRs mediate tumor cell proliferation, migration, invasion, metastasis, and angiogenesis; YR antagonists block the previous actions and promote the death of cancer cells. NPY favors tumor cell growth, migration, and metastasis and promotes angiogenesis in some tumors (e.g., breast cancer, colorectal cancer, neuroblastoma, pancreatic cancer), whereas in others it exerts an antitumor effect (e.g., cholangiocarcinoma, Ewing sarcoma, liver cancer). PYY or its fragments block tumor cell growth, migration, and invasion in breast, colorectal, esophageal, liver, pancreatic, and prostate cancer. Current data show the peptidergic system's high potential for cancer diagnosis, treatment, and support using Y2R/Y5R antagonists and NPY or PYY agonists as promising antitumor therapeutic strategies. Some important research lines to be developed in the future will also be suggested.

Non-L-cell immunophenotype and large tumor size in rectal neuroendocrine tumors are associated with aggressive clinical behavior and worse prognosis

According to the 2010 World Health Organization classification, all gastrointestinal neuroendocrine tumors (NETs) are classified as malignant except for L-cell-type (glucagon-like peptide [GLP] and peptide YY [PYY]-producing) NETs. However, L-cell immunophenotype in rectal NETs has not been widely studied previously. Immunohistochemical labeling of L-cell markers with GLP1 and PYY was performed in 208 surgically or endoscopically resected rectal NET cases with tissue microarrays and was compared with clinicopathologic features and patient survival. Rectal NETs with non-L-cell immunophenotype and large tumor size (>1 cm) were associated with increased tumor grading, advanced T category, lymphovascular and perineural invasions, and lymph node and distant metastases (P<0.001, each). Rectal NET patients with non-L-cell phenotype and measuring >1 cm had significantly worse survival outcome than other groups by univariate (P<0.001) and multivariate (P<0.001) analyses. In summary, non-L-cell immunophenotype and large tumor size are associated with increased tumor grading and staging, concurrently indicating that they are independently poor prognostic indicators in rectal NET patients. Therefore, combining L-cell phenotype and tumor size can demonstrate the clinical behavior of rectal NETs more precisely than use of L-cell immunophenotype alone.

Cocaine- and amphetamine-regulated transcript in neuroendocrine tumors

BACKGROUND/AIMS

Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic regulatory peptide highly expressed in the brain's appetite control centers, but also in peripheral neurons and in endocrine cells in the adrenal medulla, thyroid, pancreatic islets, and in the gastrointestinal tract. Plasma levels of CART were recently shown to be elevated in patients with neuroendocrine tumors (NETs), but the cellular sources of CART in NETs have remained unknown. The aim of the study was to establish whether CART is expressed in various types of NETs and, if so, to examine the frequency, distribution and phenotype of CART-expressing cells.

METHODS

Tumor specimens from 133 NETs originating in the stomach, ileum, rectum, pancreas and thyroid were examined with immunohistochemistry and in situ hybridization. The expression of CART was quantified and the CART-expressing cells were phenotyped by double staining for established markers and hormones.

RESULTS

CART-expressing tumor cells were found in the majority of the examined NETs. The expression pattern of CART was highly heterogeneous not only between tumors, but also within individual tumors. In 14% of the NETs, CART was found in a major population of the tumor cells.

CONCLUSION

CART is produced in the majority of NETs, regardless of tumor origin. This likely explains the elevated levels of circulating CART in certain NETs patients, as recently described. CART could therefore prove to be a useful tool in the diagnostics of NETs not only in blood samples, but also in histopathological specimens.

Peptide YY induces enterocyte proliferation in a rat model with total enteral nutrition after distal bowel resection

The main reason why enterocyte proliferative effects of peptide YY (PYY) have not been detected in rats undergoing massive small intestinal resection after feeding may have been the background activity of markedly increased endogenous PYY released from L cells in the distal gut in response to the intraluminal nutrients. The purpose of the present study was to evaluate the effects of PYY on enterocyte proliferation in a rat model of distal bowel resection (DBR) with total enteral nutrition (TEN). Male, adult Sprague-Dawley rats were assigned into three experimental groups: sham rats underwent bowel transection and reanastomosis, DBR rats underwent the resection of 40 cm distal small intestine and colon, and DBR-PYY rats underwent distal bowel resection as above, and were treated with PYY(1-36) from day 2 to day 14 postoperatively. During days 2-14 postoperatively, all animals received isocaloric TEN. At the endpoints, plasma PYY levels and parameters of enterocyte proliferation were determined. Compared with the sham group, DBR rats demonstrated a significant decrease in plasma PYY levels, and a significant increase in intestinal bowel and mucosal weight, mucosal DNA and protein content, villus height and crypt depth, and crypt cell proliferation index. Administration of PYY (DBR-PYY group) led to a significant increase in plasma PYY levels, intestinal bowel and mucosal weight, mucosal DNA and protein content, villus height and crypt depth, and crypt cell proliferation index in comparison with the DBR untreated group. We conclude that administration of PYY increases the plasma PYY levels, and PYY induces enterocyte proliferation with TEN after distal bowel resection.

Peptide YY and cancer: current findings and potential clinical applications

Peptide YY (PYY) is a naturally occurring gut hormone with mostly inhibitory actions on multiple tissue targets. PYY has been identified in several carcinoid tumors and a decreased expression of PYY may be relevant to the development and progression of colon adenocarcinoma. Treatment with PYY decreases growth in pancreatic and breast tumors, most likely through a reduction in intracellular cAMP. In cancer patients, PYY may also improve malnutrition that results from iatrogenic causes or cachexia associated with advanced disease. PYY plays a significant role in multiple aspects of cancer from regulation of cell growth to potential therapeutic applications.

Recovery from Marie-Bamberger's syndrome and diabetes insipidus after removal of a lung adenocarcinoma with neuroendocrine features

A 44-year-old woman with Marie-Bamberger's syndrome and diabetes insipidus had a lung tumour with mediastinal metastases, but no signs of metastases to the hypothalamus or pituitary gland. A week after removal of the tumour, the joint pain, polyuria and polydipsia disappeared. The tumour was diagnosed histopathologically as a moderately differentiated adenocarcinoma with focal neuroendocrine cell differentiation and dispersed cells reacting with antisera against neurone-specific enolase, S-100 protein, neuropeptide Y, follicle-stimulating hormone, substance P, vasoactive polypeptide (VIP), adrenocorticotropic hormone and pancreatic polypeptide (PP) as well as to one of three tested antisera raised against antidiuretic hormone (ADH). It was suggested that Marie-Bamberger's syndrome might be caused by one of these immunoreactive substances or by a substance that shares an amino acid sequence with one of these neuroendocrine peptides. It was also suggested that the tumour might produce an ADH-like substance which might have an ADH-antagonist effect.

Adenoendocrine cell carcinoma of the gallbladder: a histochemical and immunohistochemical study

A case of adenoendocrine cell carcinoma of the gallbladder with adenomucous cells and neuroendocrine cells is reported. A histochemical and immunohistochemical study revealed that the primary tumor in the gallbladder was composed of mucus-secreting and/or argyrophil cells. Furthermore, the tumor showed a positive reaction to carcinoembryonic antigen (CEA) in all tumor cells, to chromogranin A and cytokeratin in many tumor cells, to endocrine granule constituent (EGC) in some tumor cells, and to serotonin and somatostatin in a few tumor cells. In addition, a few mucous cells showed argyrophilia and EGC-positivity in their cytoplasms. This case suggests that the adenoendocrine cell tumor is derived from endodermal stem cells as a result of bidirectional (exocrine and endocrine) differentiation.

Peptide YY in the mammalian pancreas: immunocytochemical localization and immunochemical characterization

Peptide YY (PYY) was demonstrated by immunochemical and/or immunocytochemical methods in endocrine cells in the pancreas of adult mice, rats, guinea-pigs, cats, dogs, pigs and cows. In the pancreas of mouse and rat, immunoreactive PYY was observed in a major subpopulation of the glucagon cells (splenic lobe of the pancreas); immunoreactive PYY also occurred in a subpopulation of the pancreatic polypeptide (PP) cells (duodenal lobe), and in a few extra-insular endocrine cells dispersed throughout the pancreatic parenchyma. In the pancreas of cat, dog and pig immunoreactive PYY was found to coexist with PP, but not with glucagon. Radioimmunoassay (RIA) revealed PYY-like material in extracts of pancreas (and colon) of all the species examined. The highest concentrations were found in the pancreas of cat and mouse; moderate amounts were found in the rat and only small amounts were detected in guinea-pig and pig. The concentrations in the pancreas were uniformly much lower than those in the colon. Analysis by high performance liquid chromatography (HPLC) showed that the PYY-immunoreactive material from pancreas (and rat colon) had an elution profile very similar to that of synthetic PYY, and distinct from that of PP and neuropeptide Y.

Functioning ovarian carcinoids induce severe constipation

Five patients with ovarian carcinoid who had severe constipation for a long period preoperatively showed marked reduction of this symptom postoperatively. Because this phenomenon was believed to be caused by some biologically active substance rather than a mechanical effect of the tumor, reactivity to 17 amine and peptide hormones was studied immunohistochemically in these patients. Numerous peptide YY (PYY)-positive cells were detected, with PYY-positive cells representing more than 50% of all carcinoid tumor cells in each patient. PYY, which has a pharmacologic inhibitory action on intestinal motility, was presumably the cause of the constipation in these patients.

Rectal and colonic carcinoids. A clinicopathologic study of 84 cases

Eighty-four carcinoids of the colon and rectum were studied with emphasis on prognostic features, immunohistochemical characteristics, and pitfalls in diagnosis. Follow-up data were available on 35 patients. Tumors with adenocarcinomatous components, or those resembling small cell carcinomas of the lung, were excluded. Eighty-one tumors were in the rectum and three tumors were in the distal sigmoid colon. Neuron-specific enolase, chromogranin, and Leu-7 were positive in 87%, 58%, and 53% of the tumors, respectively. Hormones were positive in the following percentages: serotonin, 45%; pancreatic polypeptide, 46%; glucagon, 10%; gastrin, 3%; somatostatin, 3%; adrenocorticotrophic hormone, 1%; cholecystokinin, 0%; calcitonin, 0%; and insulin, 0%. Many tumors elaborated more than one hormone. Fifty-five percent of the tumors were argyrophil and 28% were argentaffin. Carcinoembryonic antigen was present in 24% of the tumors; 82% of the tumors contained prostatic acid phosphatase. Three patients had liver metastases; their tumors ulcerated, invaded muscularis propria, and had more than 2 mitoses per 10 high-power fields (HPF). One patient with a 2.5-cm tumor without mitoses had regional lymph node metastases. All non-metastasizing tumors had less than one mitosis in 10 HPF. We conclude that large bowel carcinoid tumors are essentially limited to the rectum and sigmoid, that they are indolent if mitotically inactive and smaller than 2 cm, and that most show production of a selected group of endocrine markers.

Argyrophil, non-argentaffin carcinoids of the appendix vermiformis. Immunohistochemical and ultrastructural studies

Five argyrophil, non-argentaffin classical carcinoids of the appendix were found in 19 appendiceal classical carcinoids and were investigated histochemically, immunohistochemically and ultrastructurally. All tumors consisted entirely of argyrophil cells. Three of the five carcinoids were composed almost totally of peptide YY cells and were negative for serotonin. One of them consisted of peptide YY cells (60%), somatostatin cells (40%), and a few cells with glucagon-like immunoreactivity (GLI). The remaining one without peptides was homogeneously immunoreactive for serotonin alone. Ultrastructurally, each of the four peptide-positive carcinoids was composed of one kind of endocrine cell type with round secretory granules. Average diameter of granules were 150, 160, 190, and 210 nm, respectively. The non-argentaffin, serotonin-positive carcinoid showed predominant round secretory granules and a few irregular ones, both being 150 nm in largest diameter. It is suggested that the argyrophil, non-argentaffin carcinoids of the appendix are subdivided into two groups; carcinoids composed mainly of peptide (especially, peptide YY)-positive cells with round granules of D1 and/or L cell type and those of serotonin-positive cells with pleomorphic granules of ECn cell type.

Glucagon, glicentin, proglucagon, PYY, PP and proPP-icosapeptide immunoreactivities of rectal carcinoid tumors and related non-tumor cells

Glucagon/PP-related peptides were detected immunohistochemically in 18 out of 22 cases of rectal tumors investigated. The reactive tumors showed prevalence of trabecular or mixed trabecular-acinar structure and moderate staining with Grimelius' silver and lead-hematoxylin. Three of the remaining 4 cases were characterized by reactivity for 5-hydroxytryptamine only, prevalence of a solid nest structural component and intense staining with Grimelius' silver technique and lead-hematoxylin. Fifteen of the 18 glucagon/PP-reactive cases were investigated immunohistochemically with a series of 6 sera directed against different sequences of glucagon, glicentin and proglucagon, and of 7 sera directed against PP, PYY and proPP-icosapeptide. A large spectrum of glucagon-related immunoreactivities, including C-terminus and mid-portion glucagon-immunoreactivity, N- and C-terminus glicentin-immunoreactivity, GLP1- and GLP2-immunoreactivity, were detected in human rectal L cells and most rectal carcinoids. With the exception of a few scattered cells in the rectal mucosa and in 3 tumors, C-terminus glucagon-immunoreactivity was obtained only after trypsin or subtilisin treatment of tissue sections. Both PYY and PP/proPP-like peptide(s) were detected in rectal L cells and carcinoids, with prevalence of PYY in normal cells and PP/proPP-like peptides in tumor cells. It is concluded that the same or closely related hormone/prohormone sequences are synthesized and stored in rectal endocrine cells and carcinoid tumors although differences of quantitative expression, post-translational cleavage or reactivity to antibodies may occur. The usefulness of protease treatments of tissue sections to unmask immunoreactivities of uncleaved propeptides or fixative-denatured peptides is outlined.

Peptide YY immunoreactive cells in gastrointestinal carcinoids: immunohistochemical and ultrastructural studies of 60 tumors

The distribution and frequency of peptide YY (PYY) cells in 60 gastrointestinal carcinoids and in the nonneoplastic mucosa around the carcinoids were studied by an indirect immunoperoxidase method with anti-PYY serum. Additionally, the endocrine cell type of the PYY cells in appendiceal and rectal carcinoids was assessed by transmission electron microscopy. A few PYY cells were present in specimens of nonneoplastic mucosa from stomach, duodenum, jejunum, ileum, and appendix, with an abundance of these cells in rectal mucosa. Peptide YY cells were found in one of 13 gastric, one of 13 duodenal, one of one jejunal, zero of two ileal, three of 11 appendiceal, and 16 of 20 rectal carcinoids. All but one of the PYY-positive carcinoids were argyrophil carcinoids. Peptide YY cells in the gastric, duodenal, and jujunal carcinoids were present in small numbers. The three PYY-positive carcinoids of the appendix were composed almost totally of PYY cells, whereas those of the rectum generally contained only sporadic PYY cells. The peptide YY cells observed ultrastructurally contained almost round secretory granules (about 160 nm in average diameter), which were most consistent with D1(H) cell type granules with respect to shape and average diameter. This is the first systematic immunohistochemical and ultrastructural study of PYY cells in gastrointestinal carcinoids.

What's new in endocrine factors of tumor growth?

In this review some aspects of endocrinological factors in cancer are discussed. The first part addresses the determination of steroid hormone receptors in cancer of the breast. The importance of steroid hormone receptor determination for the clinical management of breast cancer patients is emphasized. Current methods for receptor measurement are critically evaluated and it is concluded that rigorous standardization of tissue handling procedures and of radiochemical methodology is mandatory to improve the reliability of the presently available methods. The development of new techniques for receptor determination has been met with high expectations. Monoclonal antireceptor antibodies in principle allow the development of a radioimmunoassay but are not widely available as yet. Histochemical methods for receptor localization have so far failed to meet accepted criteria of specificity. Therefore radiochemical determination at present remains the only reliable method. The second part addresses the production of peptide hormones by endocrine tumours of the gastroenteropancreatic (GEP) system and by non-neuroendocrine neoplasms. In the endocrine tumours of the GEP system a wide range of peptide hormones can be detected by immunocytochemistry, but most frequently the pattern of hormone production is comparable with that in the normal organ of origin. Clinical symptoms of excess hormone production occur much less frequently than hormone production is found by immunological methods and is usually caused by one hormone. It is proposed that these neoplasms are classified according to the hormone which causes the leading clinical symptoms and/or the hormone with the highest serum level. Peptide hormone producing cells in classical carcinoma are an intriguing phenomenon which has shed some new light on the embryological origin of neuroendocrine cells in the relevant organs and also on the histogenesis of neuroendocrine as well as non-neuroendocrine neoplasms.

Neuropeptide Y and peptide YY neuronal and endocrine systems

An extensive system of neuropeptide Y (NPY) containing neurons has recently been identified in the central and peripheral nervous system. In addition, NPY and a structurally related peptide, peptide YY (PYY), containing endocrine cells have been identified in the periphery. The NPY system is of particular interest as the peptide coexists with catecholamines in the central and sympathetic nervous system and adrenal medulla. Evidence has been presented which indicates that NPY may play important roles in regulating autonomic function.

Nuclear DNA record in a malignant rectal carcinoid. A case report

A colo-rectal resection was performed on a 73-year-old woman with a preoperative diagnosis of rectal carcinoma. Morphological examination of the specimen revealed a rectal carcinoid tumor with regional lymph node and liver metastases. Silver stains demonstrated an argyrophil reaction in the tumor cells, but the argentaffin reaction and immunocytochemistry with monoclonal serotonin antibodies were negative. Imprint cytology of the tumor was examined cytofluorometrically and diploid nuclear DNA values were recorded with only few tetraploid cells (less than 2%.). It is suggested that diploid nuclear DNA values and a low proliferative activity are characteristic of malignant rectal carcinoids.