bromochloroacetic-acid and Insulinoma

We describe an insulinoma of the pancreas in a 56-year-old patient, which showed insular-ductular differentiation in its liver metastasis. Although the primary tumor was uniformly endocrine in nature with insulin production, the metastasis contained two distinct cell types in organoid arrangement. One cell type was insulin-positive and was arranged in islet-like structures; the other was insulin-negative but distinctly pan-cytokeratin and cytokeratin 7 positive and arranged in ducts. In the primary tumor and the metastasis, the tumor cells were surrounded by a desmoplastic stroma. As to the histogenesis of the tumor and its metastasis, we discuss the following possibilities: (1) the tumor cells might derive from a common stem cell that matures into two phenotypically different cell lines, resembling the situation in embryogenesis and (2) one tumor cell type originates from the other by transdifferentiation (metaplasia). We conclude that the parallel occurrence of endocrine and ductal differentiation supports the concept that, under certain conditions, islet cells and ductular cells may also originate from islets and that mixed endocrine/exocrine pancreatic tumors do not necessarily arise from totipotent duct cells but might also have a primary endocrine cell origin.

Topics: Biomarkers, Tumor; Carcinoma, Pancreatic Ductal; Cell Transformation, Neoplastic; Humans; Insulin; Insulinoma; Keratin-7; Keratins; Liver Neoplasms; Male; Middle Aged; Neoplastic Stem Cells; Pancreas; Pancreatic Neoplasms

Expression of cytokeratin (CK) 7 and 20 is commonly used to help distinguish adenocarcinomas from different sites. Thyroid transcription factor 1 (TTF-1) is a 38-kd protein, located primarily in the nucleus of type 2 pneumocytes and clara cells. TTF-1 has been shown to be present in a variety of lung and thyroid tumors and in pulmonary small-cell carcinomas. Carcinoid tumors from the lung and the gastrointestinal (GI) tract are histologically similar and thus are difficult to differentiate from each other based on histologic criteria. Pancreatic endocrine tumors (PET) have a similar histologic appearance to these other tumors. The purpose of this study was to determine the efficacy of differentiating these 3 groups of tumors by their expression of CK7, CK20, and TTF-1. Routinely processed paraffin-embedded tissue sections from 62 carcinoid tumors (lung, 16; gastrointestinal [GI] tract, 46) and 12 PETs were immunohistochemically stained for CK7, CK20, and TTF-1. The degree of expression in each tumor was graded as 1+ (1% to 10% of cells positive), 2+ (11% to 25%), 3+ (26% to 50%), and 4+ (>50%). The data were compared between tumor types and between carcinoid tumors from the various locations in the GI tract (stomach, 8; small intestine, 19; large intestine, 17; appendix, 2). CK7 was expressed in 10 (63%) of 16 pulmonary carcinoid tumors and only 5 (11%) of 46 GI carcinoid tumors (P <.001). Pancreatic endocrine tumors showed CK7 positivity in 6 (50%) of 12 cases, which was similar to the findings in lung carcinoids and significantly higher than in GI carcinoids (P <.01). CK20 was expressed in 0 (0%) of 16 pulmonary carcinoid tumors, in contrast to 24% and 33% of GI carcinoid tumors (P <.05) and PETs (P <.05), respectively. TTF-1 expression was highly specific for pulmonary carcinoid tumors. This peptide was present in 11 (69%) of 16 pulmonary carcinoid tumors and in only 1 (2%) of 46 and 0 (0%) of 12 GI carcinoid tumors (P <.001) and PETs (P <.001), respectively. A CK7(+)/CK20(-)/TTF-1(+) immunopanel result was moderately sensitive (sensitivity, 50%), and highly specific (specificity, 100%), for a diagnosis of pulmonary carcinoid tumor. CK7, CK20, and TTF-1 did not differ significantly between carcinoid tumors located in different sites of the GI tract. However, a trend was observed toward a lower prevalence of CK20 positivity in gastric tumors (P =.06) than in GI carcinoid tumors from the small intestine, colon, or appendix. Expression of CK7 and CK20, an

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Carcinoid Tumor; Diagnosis, Differential; Female; Gastrointestinal Neoplasms; Humans; Immunoenzyme Techniques; Insulinoma; Intermediate Filament Proteins; Keratin-20; Keratin-7; Keratins; Lung Neoplasms; Male; Middle Aged; Neoplasm Staging; Nuclear Proteins; Thyroid Nuclear Factor 1; Transcription Factors

In the present study we have evaluated the expression of different beta-cell markers, islet molecules and auto-antigens relevant in diabetes autoimmunity by a human insulinoma cell line (CM) in order to define its similarities with native beta cells and to discover whether it could be considered as a model for studies on immunological aspects of Type 1 diabetes. First, the positivity of the CM cell line for known markers of neuroendocrine derivation was determined by means of immunocytochemical analysis using different anti-islet monoclonal antibodies including A2B5 and 3G5 reacting with islet gangliosides, and HISL19 binding to an islet glycoprotein. Secondly, the expression and characteristics of glutamic acid decarboxylase (GAD) and of GM2-1 ganglioside, both known to be islet autoantigens in diabetes autoimmunity and expressed by human native beta cells, were investigated in the CM cell line. The pattern of ganglioside expression in comparison to that of native beta cells was also evaluated. Thirdly, the binding of diabetic sera to CM cells reacting with islet cytoplasmic antigens (ICA) was studied by immunohistochemistry. The results of this study showed that beta cell markers identified by anti-islet monoclonal antibodies A2B5, 3G5 and HISL-19 are expressed by CM cells; similarly, islet molecules such as GAD and GM2-1 ganglioside are present and possess similar characteristics to those found in native beta cells; the pattern of expression of other gangliosides by CM cells is also identical to human pancreatic islets; beta cell autoantigen(s) reacting with antibodies present in islet cell antibodies (ICA) positive diabetic sera identified by ICA binding are also detectable in this insulinoma cell line. We conclude that CM cells show close similarities to native beta cells with respect to the expression of neuro-endocrine markers, relevant beta cell autoantigens in Type 1 diabetes (GAD, GM2-1, ICA antigen), and other gangliosides. Therefore, this insulinoma cell line may be considered as an ideal model for studies aimed at investigating autoimmune phenomena occurring in Type 1 diabetes.

Topics: Autoantigens; Biomarkers; Chromatography, High Pressure Liquid; Diabetes Mellitus, Type 1; Gangliosides; Humans; Immunoblotting; Immunohistochemistry; Insulinoma; Islets of Langerhans; Keratins; Models, Immunological; Pancreatic Neoplasms; Tumor Cells, Cultured

This report describes the cytoskeleton nature of a 60,000-mol-wt protein, P60, previously shown to undergo Ca2+ influx-induced phosphorylation concomitant with insulin release in hamster insulinoma cells. Four lines of evidence suggest that P60 is an intermediate filament protein of the keratin class. (a) As previously described (Schubart, U.K., 1982, J. Biol. Chem. 257:12231-12238), Triton X-100-insoluble cytoskeletons are enriched for P60; (b) these cytoskeletons contain 7-11-nm filaments as determined by negative staining; (c) immunoblot analysis revealed that all proteins detected in the insulinoma cell cytoskeletons are recognized by a monoclonal antibody that interacts with a common determinant in all intermediate filament proteins; and (d) P60 was shown, by its identical migration on two-dimensional electrophoresis and by its immunologic relatedness, to be analogous to a known keratin present in HeLa cells. An antibody specific for P60, as judged by immunoblotting, was developed in a rabbit. In indirect immunofluorescence studies on insulinoma cells, this anti-P60 antibody produced a filamentous staining pattern. The antibody also permitted the identification of P60 in normal pancreatic islets as determined both by immunoblotting of hamster islet proteins resolved by two-dimensional electrophoresis and by indirect immunofluorescence microscopy on cryostat sections of hamster pancreas. In addition, the antibody recognized an antigen in the epithelial layer of pancreatic exocrine ducts, as determined by indirect immunofluorescence. The data have implications for the embryonic origin of pancreatic islets. Together with the phosphorylation data, these findings suggest that this islet cell cytokeratin may be involved in the regulation of insulin release.

Topics: Adenoma, Islet Cell; Animals; Calcium; Cricetinae; Cytoskeleton; HeLa Cells; Humans; Insulinoma; Intermediate Filament Proteins; Islets of Langerhans; Keratins; Phosphoproteins

A bronchial P cell carcinoid, which was negative for all hormones immunocyto chemically tested, showed a globular intracytoplasmic inclusion in almost every cell. The inclusions were not clearly distinguishable using the haematoxylin- eosin- safran procedure; they were best demonstrated with the Masson trichrome stain and the Grimelius technique and were easily detected in 1 micron thick Epon sections as target-like structures. On electron microscopy, they were found to be composed of filamentous aggregates entrapping a few endosecretory granules, which showed degenerative changes. The filaments, 8-10 nm in diameter, lacked any periodicity; they were randomly dispersed in the central area and arranged in broken concentric swirls at the periphery of the inclusions. The globules lacked the tinctorial properties of amyloid, but showed a strong immunostaining for keratin-like proteins. A systematic investigation of 12 APUDomas of bronchial or duodenopancreatic origin, using both light and electron microscopy, identified a few filamentous bodies in one case, a somatostatin cell tumour of ampulla of Vater. In both cases, the structures appeared similar to those previously reported in growth hormone cell pituitary adenomas as well as in a few bronchial or gut carcinoids. Whatever their nature, morphological data suggest that they are related to abnormalities in the secretory function, involving the Golgi apparatus, the endosecretory granules and the microtubular microfilamentous system.

Topics: Adult; Ampulla of Vater; Apudoma; Bronchial Neoplasms; Carcinoid Tumor; Common Bile Duct Neoplasms; Duodenal Neoplasms; Female; Humans; Immunoenzyme Techniques; Inclusion Bodies; Insulinoma; Keratins; Pancreatic Neoplasms; Protein Precursors