Expression of the DNA mismatch repair proteins (hMLH1 and hMSH2) in infiltrating pancreatic cancer and its relation to some phenotypic features

DNA mismatch repair system defects cause microsatellite instability (MSI) and form an alternative pathway in cancer development. Germline mutations of DNA mismatch repair genes account for hereditary nonpolyposis colorectal cancer, which has a different morphology and biology than sporadic cancers. MSI has also been found in sporadic neoplasms and some inflammatory conditions (chronic pancreatitis, ulcerative colitis). The purpose of the present study was to evaluate the expression of hMLH1 and hMLH2 proteins in infiltrating pancreatic cancer and to find out whether there is a relationship between some phenotypic manifestations and expression of MMR genes. We studied 30 cases of infiltrating pancreatic cancer and apart from hMLH1 and hMLH2 expression cytokeratin 7 and chromogranin were measured as markers of ductal and endocrine differentiation, respectively. All ductal pancreatic cancers expressed cytokeratin 7. In most cases the expression was strong, present in 50-100% of cells in moderately differentiated cancers and in 80-100% of cells in poorly differentiated cancers. Chromogranin expression was seen in 5 moderately differentiated cancers and in 6 poorly differentiated cancers (up to 20% of positive cells). In all cases DNA mismatch repair genes expression was present.

CONCLUSION

Ductal pancreatic carcinomas express hMLH1 and hMLH2 proteins irrespective of their differentiation. The expression of cytokeratin 7 is typical of ductal pancreatic carcinoma and its level is related to cancer differentiation. Some ductal pancreatic carcinomas irrespective of their differentiation show the expression of chromogranin, which is associated with the expression of hMSH2 gene.

Congenital neuroblastoma with multiple metastases: a case report

Neuroblastomas are derived from the neural crest ectoderm, and are the most common solid abdominal masses of infancy. Congenital neuroblastoma, however, is rare. We report a rare case of congenital neuroblastoma with multiple metastases found at autopsy, performed at 2 days after birth. He was born by cesarian section and weighed 2,350 g. His respiration was weak and abdomen was distended. The patient died 2 days after birth. Postmortem examination revealed a relatively well demarcated ovoid mass, in the left adrenal, with necrosis and hemorrhage. Multiple small metastatic tumor nodules in the liver, lung, kidney, brain, rib, thyroid glands, and spleen, were noted. The histopathological pictures confirmed the diagnosis of neuroblastoma of the adrenal with multiple metastasis.

Primary sequence characterization of catestatin intermediates and peptides defines proteolytic cleavage sites utilized for converting chromogranin a into active catestatin secreted from neuroendocrine chromaffin cells

Catestatin is an active 21-residue peptide derived from the chromogranin A (CgA) precursor, and catestatin is secreted from neuroendocrine chromaffin cells as an autocrine regulator of nicotine-stimulated catecholamine release. The goal of this study was to characterize the primary sequences of high molecular mass catestatin intermediates and peptides to define the proteolytic cleavage sites within CgA that are utilized in the biosynthesis of catestatin. Catestatin-containing polypeptides, demonstrated by anti-catestatin western blots, of 54-56, 50, 32, and 17 kDa contained NH(2)-terminal peptide sequences that indicated proteolytic cleavages of the CgA precursor at KK downward arrow, KR downward arrow, R downward arrow, and KR downward arrow basic residue sites, respectively. The COOH termini of these catestatin intermediates were defined by the presence of the COOH-terminal tryptic peptide of the CgA precursor, corresponding to residues 421-430, which was identified by MALDI-TOF mass spectrometry. Results also demonstrated the presence of 54-56 and 50 kDa catestatin intermediates that contain the NH(2) terminus of CgA. Secretion of catestatin intermediates from chromaffin cells was accompanied by the cosecretion of catestatin (CgA(344)(-)(364)) and variant peptide forms (CgA(343)(-)(368) and CgA(332)(-)(361)). These determined cleavage sites predicted that production of high molecular mass catestatin intermediates requires cleavage at the COOH-terminal sides of paired basic residues, which is compatible with the cleavage specificities of PC1 and PC2 prohormone convertases. However, it is notable that production of catestatin itself (CgA(344)(-)(364)) utilizes more unusual cleavage sites at the NH(2)-terminal sides of downward arrow R and downward arrow RR basic residue sites, consistent with the cleavage specificities of the chromaffin granule cysteine protease "PTP" that participates in proenkephalin processing. These findings demonstrate that production of catestatin involves cleavage of CgA at paired basic and monobasic residues, necessary steps for catestatin peptide regulation of nicotinic cholinergic-induced catecholamine release.

Expression of molecular targets for tyrosine kinase receptor antagonists in malignant endocrine pancreatic tumors

PURPOSE

Molecular targeting with monoclonal antibodies and tyrosine kinase inhibitors is a novel approach to cancer treatment. We have examined the expression of molecular targets in patients with malignant endocrine pancreatic tumors, which is necessary to justify additional studies investigating the potential benefit from such treatment.

EXPERIMENTAL DESIGN

Thirty-eight tumor tissues from malignant endocrine pancreatic tumors were examined with immunohistochemistry using specific polyclonal antibodies with regard to the expression pattern of platelet-derived growth factor receptors (PDGFRs) alpha and beta, c-kit, and epidermal growth factor receptor (EGFR).

RESULTS

All 38 tissue specimens expressed PDGFRalpha on tumor cells, and 21 of 37 specimens (57%) expressed PDGFRalpha in tumor stroma (1 specimen was nonevaluable). Twenty-eight samples (74%) stained positive for PDGFRbeta on tumor cells, and 36 of 37 samples (97%) stained positive for PDGFRbeta in the stroma (1 specimen was nonevaluable). Thirty-five tumor tissues (92%) stained positive for c-kit, and 21 (55%) stained positive for EGFR on tumor cells. No differences were seen between syndromes or between poorly differentiated or well-differentiated tumors. Previous treatment did not influence expression pattern. Receptor expression pattern varied considerably between individuals.

CONCLUSIONS

We have found that tyrosine kinase receptors PDGFRs alpha and beta, EGFR, and c-kit are expressed in more than half of the patients with endocrine pancreatic tumors. Because these receptors represent molecular targets for STI571 and ZD1839 (tyrosine kinase inhibitors) and IMC-C225 (a monoclonal antibody), we propose that patients suffering from EPTs might benefit from this new treatment strategy. However, because of great variability in receptor expression pattern, all patients' individual receptor expression should be examined.

A comparative immunohistochemical study of spontaneous and chemically induced pheochromocytomas in B6C3F1 mice

Spontaneously occurring and chemically induced pheochromocytomas are rare in mice. That the mouse pheochromocytoma is a more appropriate animal model than that of the rat for study of human medullary adrenal tumors has been suggested. The expression of phenylethanolamine-N-methyltransferase (PNMT), the enzyme responsible for production of epinephrine from norepinephrine, is common to both mouse and human pheochromocytomas. This investigation assessed the expression of the immunohistochemical markers PNMT, tyrosine hydroxylase (TH), and chromogranin A (CGA) in spontaneously occurring and chemically induced pheochromocytomas in the B6C3F1 mouse. Spontaneous tumors were derived from control animals from 10 different studies and the pheochromocytomas from treated groups from 4 different studies. All tumors were positive for maximal TH expression. A highly significant difference in PNMT expression (p < 0.01) occurred between spontaneously occurring pheochromocytomas classified as benign or "malignant" by the criteria of toxicologic pathology. Chemically induced tumors showed intermediate PNMT staining. A marked reduction in CGA expression occurred in pheochromocytomas induced by technical grade pentachlorophenol, compared to the other three chemicals and the spontaneously occurring tumors. These findings suggest that immunohistochemistry is a reliable tool in investigating the functional capabilities of pheochromocytomas in mice. PNMT expression is a tightly regulated component of the chromaffin cell phenotype and appears to be readily lost in mouse pheochromocytomas, particularly those with aggressive characteristics.

Neuroendocrine cell type-specific and inducible expression of chromogranin/secretogranin genes: crucial promoter motifs

The chromogranin/secretogranins (Cg/Sg) are a family of soluble, acidic proteins representing major constituents in secretory vesicle cores of virtually all neuroendocrine tissues. We and others have identified the cyclic adenosine monophosphate response element (CRE) as the crucial promoter element responsible for neuroendocrine cell type-specific expression of the Cg/Sg genes. In addition to CRE, GC-rich domains in chromogranin B (CgB) and serum response element (SRE) in secretogranin II (SgII) promoters appear to play important roles in neuroendocrine cell type-specific expression of CgB and SgII genes. Nicotinic-cholinergic and peptidergic chromaffin cell stimuli evoke catecholamine secretion and augment biosynthesis of Cg/Sg genes. These stimuli signal to CgA gene transcription through the CRE in cis and through protein kinase A, protein kinase C, and mitogen-activated protein kinase and CRE-binding protein in trans. In addition to CRE, a GC-rich domain in CgB and SRE in SgII promoters also play important roles in mediating inducible expression of the CgB and SgII genes. We conclude that CRE, GC-rich domains, and SRE are crucial determinants of both cell type-specific and secretagogue-inducible expression of the Cg/Sg genes.

Neuroendocrine marker expression in cervical carcinomas of non-small cell type

Small-cell carcinomas of the uterine cervix are highly aggressive tumors. Up to 100% of these tumors express at least one neuroendocrine marker such as neuron-specific enolase (NSE), chromogranin A (CgA), and synaptophysin (SYN). In other tumor types such as non-small-cell carcinomas of the lung, colon, and prostate, the presence of these markers has been associated with a better prognosis in some studies, a worsened prognosis in others, or has had no prognostic effect in still other studies. However, little is known about their expression and prognostic significance in the common "non-small-cell" carcinomas of the uterine cervix. The primary tumors of 54 previously untreated patients with histologically confirmed non-small-cell carcinoma of the cervix uteri (squamous carcinoma, adenosquamous carcinoma, and adenocarcinoma) were analyzed by immunohistochemistry for expression of NSE, CgA, and SYN. The expression status was correlated to pathological characteristics and outcome. In addition, the expression of these markers was investigated in cervical carcinoma cell lines. None of the 54 tumors expressed NSE or CgA, although SYN was positive in five tumors (9%) of which four were squamous and one was adenocarcinoma. These five patients relapsed within the first 6 months of follow-up and four have died. Among eight cancer cell lines only one was positive for CgA and another one for SYN. We conclude that the neuroendocrine marker SYN is expressed in a small subset of non-small-cell carcinomas of the cervix and its expression seems to correlate with a poor outcome.

Influence of steroids and GnRH on biosynthesis and secretion of secretogranin II and chromogranin A in relation to LH release in LbetaT2 gonadotroph cells

The granin proteins secretogranin II (SgII) and chromogranin A (CgA) are commonly found associated with LH and/or FSH within specialised secretory granules in gonadotroph cells, and it is possible that they play an important role in the differential secretion of the gonadotrophins. In this study we have examined the regulation of the biosynthesis and secretion of SgII and CgA, in relation to LH secretion, in the LbetaT2 mouse pituitary gonadotroph cell line. Three experiments were carried out to investigate the effects of oestradiol (E2) and dexamethasone (Dex) in the presence and absence of GnRH (experiment 1), differing GnRH concentrations (experiment 2) and alterations in GnRH pulse frequency (experiment 3). In experiment 1, exposure to E2, Dex or E2+Dex, either with or without GnRH treatment, resulted in increased LH secretion. Steroids alone had no effect on LHbeta mRNA levels, but in the presence of GnRH LHbeta mRNA levels were increased in Dex- and E2+Dex-treated cells. GnRH receptor (GnRH-R) mRNA levels were up-regulated by Dex and E2+Dex, but were unaffected by GnRH. There were no steroid-induced changes in SgII or CgA mRNA, but increased levels of CgA mRNA were observed after GnRH treatment in cells cultured in the presence of Dex. In experiment 2, increasing concentrations of GnRH resulted in increases in LH secretion that were inversely dose-dependent. No changes in LHbeta, GnRH-R or SgII mRNA levels were observed, but there were dose-dependent increases in CgA mRNA levels. In experiment 3, GnRH was given as either 1 pulse/day or 4 pulses/day for 3 days. Both pulse regimes resulted in increased LH, SgII and CgA secretion compared with controls during the first 15 min pulse on day 3. Exposure to GnRH at 4 pulses/day increased LH and SgII secretion compared with controls during all 4 pulses, but secretion of both proteins was reduced during pulses 2-4 compared with pulse 1. CgA secretion also increased due to GnRH in pulse 1, but was decreased by GnRH treatment during pulse 2, and unchanged by GnRH during pulses 3 and 4. Total daily secretion of LH and SgII from cells given 1 pulse/day of GnRH increased compared with controls on all three treatment days, while total CgA secretion increased in response to GnRH on days 2 and 3 only. Intracellular levels of SgII, but not LH, decreased after GnRH treatment. In contrast, intracellular CgA was increased, but only after 4 pulses/day of GnRH. Levels of LHbeta, but not SgII, mRNA were increased by both pulse regimes, while CgA mRNA levels increased after 1 pulse/day of GnRH. These results indicate that there is a close correlation between the GnRH-stimulated release of LH and SgII from LbetaT2 cells, suggesting that SgII may have an influential role in the regulated secretion of LH, possibly by inducing LH aggregation to facilitate trafficking into secretory granules. CgA secretion does not appear to be closely associated with that of LH, but CgA expression does appear to be regulated by GnRH, which may indicate involvement in the control of LH secretion, possibly by influencing the proportion of LH in the different types of secretory granules.

Expression of chromogranin A and somatostatin receptors in pancreatic AR42J cells

The exocrine pancreatic cell line AR42J is also known to display some neuroendocrine (NE) features. We have extended this fact by showing that AR42J cells express mRNA of chromogranin A (CgA), display immunoreactivity (IR) to CgA, and secrete its cleavage product pancreastatin. A sparse occurrence of typical NE secretion granules, together with only a faint IR to conventional NE markers, indicates that the NE cells are of a poorly differentiated type. CgA promoter reporter plasmid experiments showed that gastrin, epidermal growth factor, and phorbol 12-myristate 13-acetate, induce upregulation of CgA after 24 h. By RT-PCR, it was found that AR42J expresses all of the five subtypes of the somatostatin (SST) receptor (SSTR) family, except SSTR4. The existence of functional SSTRs was confirmed by showing that the SST analog octreotide could inhibit gastrin-induced proliferation. Thus, the AR42J cell line may function as a valuable experimental model to study the regulation of CgA and SSTRs in poorly differentiated NE tumor cells.

ACTH-secreting islet cell tumor of the pancreas presenting as bilateral ovarian tumors and Cushing's syndrome

A 41-year-old woman presented with hirsutism, a pelvic mass, and Cushing's syndrome. Imaging studies revealed bilateral ovarian masses and a solid and cystic mass within the pancreas. Partial pancreatectomy, bilateral oophorectomy, and excision of several peritoneal tumor nodules were performed. Pathological examination revealed a neuroendocrine islet cell tumor of the pancreas with bilateral ovarian metastases. The tumor was immunoreactive for ACTH, chromogranin, neuron-specific enolase, and keratin. The patient received postoperative chemotherapy and has been disease-free for 6 years. To our knowledge, this is the first reported case of an ACTH-secreting pancreatic neuroendocrine tumor presenting as bilateral ovarian metastases.

Different profiles of neuroendocrine cell differentiation evolve in the PC-310 human prostate cancer model during long-term androgen deprivation

BACKGROUND

Neuroendocrine (NE) cells are androgen-independent cells and secrete growth-modulating peptide hormones via a regulated secretory pathway (RSP). We studied NE differentiation after long-term androgen withdrawal in the androgen-dependent human prostate cancer xenograft PC-310.

METHODS

Tumor-bearing nude mice were killed at 0, 2, 5, 7, 14, 21, 47, 84, and 154 days after castration. The half-life of the PC-310 tumor was 10 days, with a stable residual tumor volume of 30--40% after 21 days and longer periods of androgen deprivation.

RESULTS

Proliferative activity and prostate-specific antigen serum levels decreased to zero after castration, whereas cell-cycle arrest was manifested by increased p27(kip1) expression. A temporary downregulation of androgen receptor (AR) expression was noted after androgen deprivation. The expression of chromogranin A, secretogranin III, and secretogranin V (7B2) increased 5 days after castration and later. Subsequently, pro-hormone convertase 1 and peptidyl alpha--amidating monooxygenase as well as vascular endothelial growth factor were expressed from 7 days after castration on. Finally, such growth factors as gastrin-releasing peptide and serotonin were expressed in a small part of the NE cells 21 days after castration, but strong expression was induced late during androgen deprivation, that is, 84 and 154 days after castration, respectively.

CONCLUSIONS

Androgen deprivation of the NE-differentiated PC-310 model induced the formation of NE-differentiated AR(minus sign) and non-NE AR(+) tumor residues. The NE-differentiated cells actively produced growth factors via an RSP that may lead to hormone-refractory disease. The dormant non-NE AR(+) tumor cells were shown to remain androgen sensitive even after long-term androgen deprivation. In the PC-310 xenograft, time-dependent NE differentiation and subsequent maturation were induced after androgen depletion. The androgen-dependent PC-310 xenograft model constitutes an excellent model for studying the role of NE cells in the progression of clinical prostate cancer.

Chromogranin A expression in neoplastic cells affects tumor growth and morphogenesis in mouse models

Chromogranin A (CgA), a secretory protein expressed by many neuroendocrine cells, has been recognized as a useful tissue and serum marker of neuroendocrine tumors. To investigate the effect of CgA secretion on neoplastic morphogenesis and progression, we have transfected mouse RMA lymphoma and TS/A adenocarcinoma cells with the cDNA encoding human CgA and selected several CgA-positive (secreting) and CgA-negative (nonsecreting) clones. In both models, the growth rate of CgA-positive clones implanted s.c. in nude mice was slower than that of CgA-negative clones. Histological analysis of each RMA tumor showed that CgA-expression was associated with multinodular growth patterns, whereas CgA-negative tumors appeared more compact and similar to wild-type RMA tumors. Moreover, CgA production was associated with increased tumor necrosis. The number of nodules in each RMA tumor correlated with the serum levels of CgA (n = 40, r = 0.537, P = 0.0004). The reduced growth rate of CgA-positive RMA and TS/A tumors was not related to reduced in vitro proliferation or to changes in cell adhesion and shape, suggesting that the mechanism is indirect and host-mediated. These results suggest that abnormal secretion of CgA by neuroendocrine neoplastic cells could affect neoplastic growth and morphogenesis.

Correlation between chromogranin-A expression and pathological variables in human colon carcinoma

BACKGROUND

The possible association between neuroendocrine pattern and cancer prognosis could have substantial clinical implications, but the studies performed have generated conflicting results. As chromogranin-A (CGA) and dense-core granules are expressed concordantly, CGA expression may be used as a marker for cells expressing the complete neuroendocrine cell phenotype.

MATERIALS AND METHODS

Fifty-six patients with primary colon carcinoma who underwent potentially curative surgery were analyzed. For immunohistochemical study a monoclonal antibody specific for human chromogranin A was used. The tumor was considered positive when the number of CGA cells was higher than 10% in the section. The relation between CGA-positivity and depth of parietal invasion, lymph-node status and differentiation grade was examined.

RESULTS

We observed positive immunostaining in 22 cases out of 56 (39.3%). Significant association was found between CGA-positivity and lymph-node metastasis.

CONCLUSION

CGA overexpression could reflect a more aggressive tumor. If our results are confirmed, we should consider the CGA + colon cancer patients at risk for lymph-node disease and therefore include them in a adjuvant chemotherapeutic protocol.

The expression of neuropeptides in hyperplastic and malignant prostate tissue and its possible clinical implications

PURPOSE

We characterized the incidence and pattern of distribution of neuroendocrine differentiated tumor cells in prostatic hyperplastic and carcinomatous tissue, correlated neuroendocrine differentiation with prostate specific antigen (PSA) and assessed whether neuroendocrine cells have value as an independent indicator of poor prognosis in patients with prostate carcinoma.

MATERIALS AND METHODS

We immunohistochemically evaluated hyperplastic and carcinomatous prostate specimens for chromogranin A, neuron specific enolase and serotonin expressing tumor cells. The expression of various markers in cells was analyzed and correlated with tumor DNA ploidy, disease grade and stage, PSA and clinical course in patients with prostate cancer.

RESULTS

Enrolled in our study were 31 patients with hyperplastic prostate tissue and 30 with prostatic carcinoma. Followup in cancer cases was 1 to 9 years (mean 3.7). During followup 9 patients (30%) died of cancer. We noted DNA content aneuploidy in 5 cases (16.7%) of prostate carcinoma. Chromogranin A, neuron specific enolase and serotonin were expressed in 80%, 43% and 77% of cases of prostate carcinoma and in 29%, 10% and 36% of hyperplastic tissue, respectively. Larger prostates had no higher content of various neuroendocrine cells than smaller prostates. There was higher expression of neuropeptides in carcinomatous than in hyperplastic tissue. Of the 3 peptides chromogranin A was significantly related to all parameters, including Gleason score, tumor stage, PSA and patient survival. In addition to PSA, neuron specific enolase was also closely associated with other clinicopathological parameters. Serotonin was significantly related to patient survival only but we noted no correlation with Gleason score, tumor stage or PSA. In regard to factors predictive of patient prognosis expression of the 3 neuropeptides in tumor cells, Gleason score, tumor stage and PSA were closely related to patient survival in this study

CONCLUSIONS

The growth of hyperplastic prostate tissue is related to neuroendocrine cell activity. The chromogranin A marker has the highest expression in prostate cancer. Neuroendocrine cells may represent an independent indicator of poor prognosis in patients with prostate carcinoma.

Evidence that the chromogranin B fragment 368-417 extracted from a pheochromocytoma is phosphorylated

A rabbit antiserum was raised against a synthetic peptide corresponding to residues 403 to 417 of human chromogranin B. This peptide was chosen to match the potential C-terminal end of a putative proteolytic fragment of the protein located between dibasic doublets in positions 366-367 and in positions 418-419 of the precursor. A radioimmunoassay based on this antiserum was developed and used to detect the protein or a fragment thereof in a pheochromocytoma tumor extract. One fragment was purified to homogeneity by successive reverse-phase HPLC chromatographies. The N-terminal sequence established by automated Edman degradation, was N-Y-P-S-L-E-L-D-K-M-A-H-G-Y-G-E-E-S-E-E-E-R corresponding to the 368-389 sequence of human chromogranin B. Taking into account the specificity of the antiserum used for peptide identification and alignment with the precursor sequence, we deduced that the purified peptide was chromogranin B (368-417) and represented a new peptide generated by limited proteolysis of chromogranin B. Combining electrospray mass-spectrometry and enzymatic dephosphorylation, we demonstrated that this peptide was phosphorylated.

Proteomic analysis of proteins in PC12 cells before and after treatment with nerve growth factor: increased levels of a 43-kDa chromogranin B-derived fragment during neuronal differentiation

Proteomic analysis is an important approach to characterizing the proteome and studying protein function in the post-genomic era. It is also a powerful screening method for detecting unexpected alterations in protein expression that may be missed by conventional biochemical techniques. The aim of this study was to perform a preliminary proteomic analysis of PC12 cells in order to investigate the effect of nerve growth factor (NGF) on protein expression in PC12 cells during neurite outgrowth. PC12 cell proteins were separated by two-dimensional electrophoresis (2DE) and visualized by silver staining, then certain proteins were identified by N-terminal amino acid microsequencing and a homology search of a protein sequence database. Over 400 proteins were detected, 10% of which showed a significant (greater than 30%) increase or decrease in expression during NGF-induced neuronal differentiation. Seven proteins in the 2DE map were identified; the levels of five of these were unaffected by NGF treatment, whereas the levels of the other two, beta-tubulin and a novel 43-kDa chromogranin B-derived fragment, were significantly increased by more than 30 and 200%, respectively. Our results suggest that chromogranin B processing is enhanced in PC12 cells during NGF-induced neuronal differentiation. In addition, since this increase in the levels of the chromogranin B-derived fragment was specifically blocked by PD98059, we suggest that the increased processing can be ascribed to activation of the MAP kinase pathway, and that the 43-kDa chromogranin B-derived fragment can serve as a new marker of neuronal differentiation for proteomic studies.

Neuroendocrine cells along the digestive tract express neuropilin-2

Neuropilin-2 (np-2) is a receptor for semaphorin-3F (sema-3F) and semaphorin-3C (sema-3C). These semaphorins repel tips of growing axons that express np-2. In addition, np-2 functions as a receptor for heparin binding forms of the angiogenic factor vascular endothelial growth factor (VEGF) such as VEGF145 and VEGF165. We report that np-2 is strongly expressed in neuroendocrine cells located all along the human digestive tract. Confocal fluorescent microscopy revealed that np-2 is concentrated in vesicle-like structures located near the nucleus at the basolateral side of these cells. In the colon, the np-2-expressing subpopulation of neuroendocrine cell is almost identical with the serotonin-producing subpopulation of neuroendocrine cells. Gastrointestinal carcinoid tumors are digestive tract tumors that develop from neuroendocrine cells. Interestingly, most of the carcinoid tumors derived from the colon and the appendix did not contain np-2-producing cells. However, some carcinoid tumors derived from the small intestine and stomach did express low levels of np-2 in isolated foci of cells. By contrast, strong serotonin and chromogranin-A expression was observed in all of the carcinoid tumors that were examined. These results suggest that loss of np-2 expression may accompany tumor progression in carcinoid tumors.

Growth and characterization of a cell line from a human primary neuroendocrine carcinoma of the skin (Merkel cell carcinoma) in culture and as xenograft

The primary neuroendocrine carcinoma of the skin or Merkel cell carcinoma (MCC) is a skin tumor with aggressive biological behaviour. Experimental models for investigating the biological properties of the tumor are prerequisite for developing new therapeutic approaches. In this study, we report the establishment and characterisation of a cell line derived from the lymph-node metastasis of a patient with highly aggressive MCC. Merkel carcinoma cells (MCC-1) grew as floating aggregates in suspension cultures for more than two years and over 70 subcultures. The proliferation rate in suspension cultures was rather moderate with a population doubling time of 69 h. The immunocytochemical pattern of the cultured MCC-1 was similar to that of the original tumor with expression of cytokeratin 18, neuron-specific enolase, neurofilaments, and synaptophysin. In addition, reverse transcriptase polymerase chain reaction (RT-PCR) revealed presence of chromogranin A mRNA in the MCC-1 cell line. Furthermore, electron microscopy yielded the rare finding of neuroendocrine granules in the cytoplasm of the cultured cells. The cell line MCC-1 was able to form colonies in soft agar. Nude mice developed solid tumors with similar histology to the original tumor after subcutaneous and intravenous injections of cultured MCC-1, and malignant ascites was seen after intraperitoneal injection. Also, two MCC-1 sublines were established by reculturing cells from the xenografts grown in vivo and immunocytochemistry confirmed their neuroendocrine origin. The MCC-1 line may thus serve as a model for studying the biology and the metastatic potential of Merkel cell carcinoma.

Regulation of chromogranin biosynthesis by neurotrophic growth factors in neuroblastoma cells

Polypeptide growth factors secreted from the target tissue determine the choice of transmitter synthesis in the innervating nerves. We have investigated whether they also influence the expression of chromogranins and neuropeptide Y, components co-stored with the neurotransmitters within large dense-core vesicles. IMR-32 and SH-SY5Y human neuroblastoma cells were treated for up to six days with various neurotrophic growth and differentiation factors. For chromogranins A and B, no significant changes at the mRNA level were observed and for chromogranin A this was confirmed at the protein level. The expression of secretogranin II/pro-secretoneurin mRNA, however, was considerably enhanced in both cell lines after basic fibroblast growth factor treatment. In IMR-32 cells we determined a fast and continuous induction, whereas the up-regulation in SH-SY5Y cells was more delayed. A transient elevation of secretogranin II/pro-secretoneurin mRNA levels was seen in SH-SY5Y cells in response to epidermal growth factor. In these cells we also measured the amounts of secretogranin II/pro-secretoneurin protein which were increased by both growth factors. In addition to the above described changes in secretogranin II/pro-secretoneurin biosynthesis we extended and confirmed data available on neuropeptide Y. We found a qualitatively similar pattern of biosynthesis regulation as for secretogranin II/pro-secretoneurin, indicating that the ultimately increased expression of the two proteins may be characteristic of the phenotypic differentiation after growth factor treatment. Moreover, this finding of a concomitant regulation further emphasizes the concept of secretogranin II/pro-secretoneurin being a neuropeptide precursor from which the functional peptide secretoneurin is proteolytically liberated.

Neuroendocrine-like differentiation in patients with pancreatic carcinoma

BACKGROUND

The accurate estimation of the rate and the clinicopathologic significance of neuroendocrine-like differentiation (NED) in patients with pancreatic carcinoma have not been studied in detail.

METHODS

Forty-four patients with pancreatic carcinoma who underwent surgical resection at the Department of Surgery II, Nagoya University Hospital, were included in this study. For immunostaining, antibodies against neural cell adhesion molecule (NCAM), neuron-specific enolase (NSE), synaptophysin, CD57, and chromogranin A (CGA) were used at given dilutions. At least two positive results with antibodies were considered as NED. Statistical analysis was performed by chi-square and Spearman rank correlation tests for group differences. Survival rates were calculated by the Kaplan-Meier method, and statistical significance was examined using the log rank test. Prognostic factors were tested by univariate and multivariate analyses (proportional hazards regression model). P < 0.05 was considered statistically significant.

RESULTS

Of 44 patients examined, 20 showed NED. The distribution of patients with positive or negative NED in terms of age, tumor differentiation, tumor size, and the extent of tumor or lymph node metastasis showed no significant difference. The cumulative survival rates of patient groups according to NED status were then calculated, and NED positive patients showed a significantly better survival rate (P < 0.05). Univariate and multivariate analyses of those factors showed that only NED status and TNM stage were significantly related to overall survival.

CONCLUSIONS

The current study suggests the significance of NED status in determining the outcome of patients with pancreatic adenocarcinoma, giving solid evidence to encourage further studies on the differentiation and origin of tumor cells in the pancreas.

Molecular cloning of equine chromogranin A and its expression in endocrine and exocrine tissues

Chromogranin A (CGA) is a member of a family of highly acidic proteins co-stored and co-released with catecholamines in the adrenal medullary cells as well as in other neurons and paraneurons. The nucleotide sequence encoding equine CGA was determined using RT-PCR and rapid amplification of complementary DNA (cDNA) ends (RACE) techniques. A total 1,828 bp of the nucleotide sequence reveals that equine CGA is a 448-residue protein preceded by an 18-residue signal peptide. Comparison of the amino acid sequence of equine CGA with those of human, porcine, bovine, mouse, rat and frog CGA showed high conservation at the NH2-terminal 1-77 amino acids regions (94.8%, 93.5%, 92.2%, 81.8%, 83.1% and 66.2%, respectively) and COOH-terminal 314-430 amino acids regions (90.6%, 81.4%, 90.6%, 80.5%, 83.3% and 39.0%, respectively), as well as a potential dibasic cleavage site, whereas the middle portion showed marked sequence variation (52.5%, 49.1%, 38.9%, 26.6%, 27.9% and 6.2%, respectively). Northern blot analysis and RT-PCR elucidated the tissue distribution of equine CGA mRNA. Its expression was confirmed not only in the adrenal medullary cells but also in other organs (cerebrum, cerebellum, pituitary gland, spinal cord, liver, thyroid gland, striated muscle, lung, spleen, kidney, parotid gland and sublingual gland). Further, in adrenal chromaffin cells and pituitary cells of the anterior-intermediate lobe, the expression was confirmed by in situ hybridization with anti-sense CGA cRNA probe.

Immunohistochemical performance of antibodies on previously frozen tissue

Immunohistochemical stains are occasionally performed on paraffin-embedded, fixed material that was previously frozen, most frequently for an intraoperative frozen section diagnosis. A retrospective study comparing immunohistochemistry on previously frozen then fixed tissue with freshly fixed tissue was designed. Of 43 cases identified during the period 1994-1996 in which immunohistochemistry was performed on frozen section blocks, 19 met criteria for inclusion. Immunohistochemistry using antibodies to S-100, HMB-45, synaptophysin, chromogranin, neuron-specific enolase (NSE), neurofilament, glial fibrillary acidic protein, vimentin, and carcinoembryonic antigen (CEA) was compared. Staining for cytokeratins was unchanged. Staining for S-100, HMB-45, synaptophysin, and NSE were negative in frozen/fixed tissue and positive in comparable fresh/fixed tissue in at least one case each. Chromogranin and CEA exhibited a significant decrease in the frozen/ fixed tissue. We conclude that caution must be exercised in interpreting immunohistochemical results using tissue that was frozen for intraoperative consultation before formalin fixation and paraffin embedding.

Immunohistochemistry in the differential diagnosis of acinar and endocrine pancreatic neoplasms

Histologic differential diagnosis of acinar cell carcinoma (ACC), mixed acinar-endocrine cell carcinoma (MAEC), and pancreatic endocrine tumors (PET) can be difficult but is important because of differences in their clinical behavior. This study investigates the utility of immunohistochemistry (IHC) in this differential diagnosis using immunohistochemical stains that are available in most laboratories. IHC was performed on paraffin-embedded tissue in ACC (n = 6), MAEC (n = 2), and PET (n = 13), using synaptophysin (SYN), chromogranin (CHR), chymotrypsin (CHY), and alpha-1-antitrypsin (AAT). Electron microscopy (EM) was performed in all cases to confirm the diagnosis. Long-term follow-up and death of disease (DOD) was known in all patients. The ACCs stained as follows: CHY (4/6), AAT (3/6), SYN (4/6); CHR was negative in all cases. Both cases of MAEC stained with CHY, AAT, and SYN (2/2); CHR was negative. PET stained as follows: SYN (13/13), CHR (8/13), CHY (4/13), AAT (5/13). In the ACC/ MAEC group, six of eight patients were DOD at mean follow-up of 11 months. Among the PET, two of 16 patients were DOD at mean follow-up of 37 months. Considerable immunophenotypic overlap exists between ACC, MAEC, and PET. Consequently, one can neither confirm nor rule out a diagnosis of ACC or MAEC using generally available immunohistochemical stains alone. These findings support a role for EM in the evaluation of exocrine and endocrine pancreatic neoplasms.

Formation of the catecholamine release-inhibitory peptide catestatin from chromogranin A. Determination of proteolytic cleavage sites in hormone storage granules

The catestatin fragment of chromogranin A is an inhibitor of catecholamine release, but its occurrence in vivo has not yet been verified, nor have its precise cleavage sites been established. Here we found extensive processing of catestatin in chromogranin A, as judged by catestatin radioimmunoassay of size-fractionated chromaffin granules. On mass spectrometry, a major catestatin form was bovine chromogranin A(332-364); identity of the peptide was confirmed by diagnostic Met(346) oxidation. Further analysis revealed two additional forms: bovine chromogranin A(333-364) and A(343-362). Synthetic longer (chromogranin A(332-364)) and shorter (chromogranin A(344-364)) versions of catestatin each inhibited catecholamine release from chromaffin cells, with superior potency for the shorter version (IC(50) approximately 2.01 versus approximately 0.35 microm). Radioimmunoassay demonstrated catestatin release from the regulated secretory pathway in chromaffin cells. Human catestatin was cleaved in pheochromocytoma chromaffin granules, with the major form, human chromogranin A(340-372), bounded by dibasic sites. We conclude that catestatin is cleaved extensively in vivo, and the peptide is released by exocytosis. In chromaffin granules, the major form of catestatin is cleaved at dibasic sites, while smaller carboxyl-terminal forms also occur. Knowledge of cleavage sites of catestatin from chromogranin A may provide a useful starting point in analysis of the relationship between structure and function for this peptide.