Hormone-negative, chromogranin A-positive endocrine tumors

Immunohistological study of nonfunctional parathyroid carcinoma. Report of a case

The histological and immunohistological features of a non-functional parathyroid carcinoma obtained from a 56-year-old woman are reported. Macroscopically, the tumor consisted of many small hemorrhagic nodules and showed adhesion to the thyroid gland and esophageal wall. Histologically, the tumor cells resembled parathyroid chief cells, and showed an island-like or sheet-like arrangement, the former showing cystic degeneration and containing hemorrhagic fluid in the extracellular space. Tumor cells resembling water-clear cells and oxyphilic cells were also observed. Most of the tumor cells had glycogen in the cytoplasm. Immunohistologically, the tumor cells showed no staining with anti-thyroglobulin, JT-95 or anti-calcitonin antibodies. However, they were stained with antibodies against chromogranin A (Ch A) and the N-terminal portion of human parathyroid hormone (PTH (N)). The positive staining with anti-PTH (N) antibody disappeared when the antibody was absorbed with excess synthesized human PTH (N). Immunostaining for PTH (N) and Ch A was useful for differentiation of nonfunctional parathyroid carcinoma from thyroid carcinoma and thymoma.

Parathyroid hormone-related protein, chromogranin A, and calcitonin gene products in the neuroendocrine skin carcinoma cell lines MKL1 and MKL2

We studied the production of parathyroid-hormone-related protein, chromogranin A, calcitonin and calcitonin-gene-related peptide in the neuroendocrine skin cell line, MKL1, and a subsequently derived cell line designated MKL2. Both cell lines had cytological, histological and electron-microscopic features typical of neuroendocrine differentiation. Immunohistology and radioimmunoassay studies demonstrated the presence of parathyroid-hormone-related protein, chromogranin A, calcitonin-gene-related peptide, and calcitonin in the MKL2 cell line and the last three substances in both cell lines. The secretion of each of the first three substances was regulated by phorbol in the MKL2 cells. Additional immunohistochemical studies demonstrated the variable expression of bombesin, substance P, and vasoactive intestinal polypeptide in MKL2 cells, and the expression of synaptophysin in both MKL1 and MKL2 cells. These studies demonstrate the neuroendocrine characteristics of the MKL cell lines and provide a novel model for studies of the production and interactions of several neuroendocrine proteins and peptides by human skin cells.

Elevated plasma chromogranin-A concentrations in prostatic carcinoma

Chromogranin-A is considered a sensitive immunohistochemical tissue marker in neuroendocrine prostatic carcinoma. We report that the plasma chromogranin-A level was elevated in 48% of 25 patients with stage D2 prostate cancer, and suggest that this marker can be used to monitor the clinical course of these patients.

Solid-cystic tumour of the pancreas. An endocrine neoplasm?

Immunohistochemical studies and DNA flow-cytometric investigations were performed in a case of solid-cystic tumour of the pancreas in a 35-year-old woman. All tumour cells were immunoreactive for the neuroendocrine cell markers chromogranin A and neuron-specific gamma-enolase. Moreover, about 10% of tumour cells were immunoreactive for insulin, while hypoglycaemia was absent. Few tumour cells (less than 1%) were immunoreactive for somatostatin, and no cells were found to be immunoreactive for pancreatic polypeptide or glucagon. No immunoreactivity was present for duct cell marker carcino-embryonic antigen and only individual cells were reactive for alpha 1-antitrypsin. Nuclear DNA content of the tumour cells was diploid and the proliferative activity was low. In confirmation of some reports on neuroendocrine markers in solid-cystic tumour of the pancreas, our findings support the theory that the lesion is a hormonally inactive neuroendocrine pancreatic tumour.

Differential expression of the neural cell adhesion molecule NCAM 140 in human pituitary tumors

We have analyzed the expression of the intracellular marker protein neuron specific enolase (NSE), synaptophysin (SYN) and of the cell surface marker NCAM (neural cell adhesion molecule) in both normal hypophysis and in pituitary adenomas in order to explore their potential use as diagnostic tools. All adenomas (4 prolactinomas, 3 growth hormone (GH) producing adenomas and 4 inactive adenomas) showed SYN and NSE immunoreactivity on tissue sections and this was confirmed by immunoblots. NCAM 140 (an isoform of NCAM with molecular mass 140 kDa) was detected by immunoblotting in normal human adenohypophysis, in all GH adenomas, and in three out of four inactive adenomas, but not in prolactinomas. Using highly sensitive techniques, NCAM immunoreactivity was observed by electron microscopy in all adenomas. These data indicate that NCAM 140 is a constituent of the cell surface of endocrine cells in both normal human adenohypophysis and its tumors. Since prolactinomas express very low levels of NCAM 140 compared to other hypophyseal tumors its virtual absence could be used for differential diagnosis. A combined analysis of NCAM, SYN and NSE could be useful to characterize inactive adenomas which are not immunoreactive for pituitary hormones and which may contain no or only low levels of the alpha chain of the glycoprotein hormones.

A chromogranin A-derived peptide differentially regulates the secretion of calcitonin gene products

We studied the regulation of the secretion of CT and CGRP by chromogranin A (CgA)-derived peptides in a human lung tumor cell line. The amino-terminal peptide of CgA, CgA1-40, stimulated the secretion of CGRP and inhibited the secretion of CT; both effects occurred in a dose-dependent manner. These studies demonstrate a differential effect of a CgA-derived peptide on two products of the CT gene, CT itself and CGRP. CgA may be processed at its multiple dibasic sites to peptides that specifically regulate the secretion of its coresident hormones, in this case two calcitonin gene products that are present in the same secretory vesicle. This novel mechanism represents a new pathway for the control of calcium regulating hormones.

Distinct patterns of chromogranin A-related species can be demonstrated in endocrine cells

We have studied the pattern of chromogranin A (CgA)-related species in different human endocrine cells that produce CgA and also express the calcitonin gene. Antibodies against CgA peptides that span its linear sequence were used in Western analysis of cell lines derived from medullary thyroid carcinoma (MTC), small cell lung cancers (SCLC), epidermoid cell lung cancer (ECLC) and a pulmonary carcinoid tumor (CRND). Each of the cell lines demonstrated a distinct pattern of CgA-related species. Gel filtration studies also revealed multiple and different forms of immunoreactive CgA in the cell lines. Although proteolysis may contribute to our results, these observations suggest that native CgA is processed to smaller species in a tissue-specific pattern by different endocrine cells. More conclusive studies, however, are necessary to establish that cell processing leads to the specific CgA moieties that we have observed.