Chromogranin A alters ductal morphogenesis and increases deposition of basement membrane components by mammary epithelial cells in vitro

Novel biomarkers in heart failure: an overview

Heart failure is a complex systemic syndrome resulting from significant impairment of cardiac function. A vast array of biological pathways is now known to be involved in heart failure, including deleterious pathways promoting its development and progression, as well as compensatory cardioprotective pathways. Some of the components of these pathways are now recognized as biomarkers of this condition, and can aid diagnosis, prognostication and guide management. As the understanding of the pathophysiology of heart failure progresses, further candidate biomarkers are being identified. This article reviews the literature regarding the more recently identified biomarkers and outlines areas requiring further study.

Neuroendocrine carcinoma of the liver and gallbladder in a cow

A 15-year-old Limousin-cross cow was presented for examination with neurological signs and serum biochemical changes consistent with liver disease. Necropsy revealed enlargement of the liver with multifocal firm, depressed, pale, circumscribed lesions throughout the parenchyma. Within the gallbladder there were exophytic and villiform mucosal masses. Microscopically, hepatic structure was displaced by neoplastic cells forming trabeculae, nests and rosettes. There was transmural infiltration of the gallbladder by similar cells. The histological pattern of growth of the neoplastic cells, the presence of silver-stained cytoplasmic granules within these cells and the immunohistochemical demonstration of chromogranin A supported the diagnosis of neuroendocrine carcinoma. Bovine liver and gallbladder neuroendocrine carcinomas are rare and this is the first detailed documentation of the disease in the United Kingdom.

Plasma and tissue chromogranin in patients with adrenocortical adenomas

Adrenal adenomas frequently arise from cortical islets in the medulla, and these islets seem to present a greater risk for pathological growth than cortical cells within the adrenal cortex. Chromogranin A (CgA), a glycoprotein co-stored in secreting granules and co-released with resident hormones of chromaffin cells, behaves as a prohormone, generating several biologically active peptides capable of influencing growth, morphogenesis and progression of endocrine tumors. The aim of our study was to investigate whether chromaffin cells may be involved in the development and growth of adrenocortical adenomas. We enrolled 19 patients (12 females and 7 males, mean+/-SD age 54.9+/-11.2 yr, age range 34-75 yr) with incidental, non-functioning, benign adrenocortical adenomas, and measured circulating levels of CgA, catecholamines and creatinine before and 2 months after surgery. Plasma CgA was evaluated by immunoradiometric assay. Testing for CgA immunoreactivity in the removed tissues was performed by immunohistochemical analysis. Mean plasma CgA did not significantly change following surgery (before 73.7+/-15.2 ng/ml; after 68.9+/-14.8 ng/ml). Individual CgA values indicated that 4 patients had plasma CgA levels above our cut-off of normality. After mass removal, CgA further increased in 2 cases, decreased in 1 and normalized in 1. No variation in CgA levels was found in the other patients. No correlation was observed between CgA and the variables measured, except between CgA and plasma creatinine (r=0.472, p<0.05). Histopathological evaluation revealed adrenocortical adenomas in all cases and immunohistochemical analysis detected no CgA immunoreactivity in any specimen. Our results show that in human adrenocortical adenomas CgA is not expressed and that removal of the mass does not modify plasma CgA levels. For these reasons the endocrine involvement of local CgA in adrenocortical tumorigenesis is unlikely.

Chromogranin a processing in human pituitary adenomas and carcinomas: analysis with region-specific antibodies

The expression of various chromogranin A (CgA) peptide fragments was examined with region-specific antisera in benign and malignant pituitary tumors. Analysis of the proconvertases responsible for proteolytic processing of CgA, prohormone convertase 1/3 (PC1/3), and PC2 was also performed. Adenomas were studied using tissue microarrays, and a larger tissue section of a subset of the prolactin (PRL) adenomas was used to compare to the tissue microarray analysis. Carcinomas were analyzed using larger tissue sections. There were differences in CgA proteolytic products detected between the functional (PRL, adrenocorticotropic hormone [ACTH], and growth hormone tumors and the nonfunctional (gonadotroph and null cell) tumors, with the former group expressing lower levels of many peptides. These differences were most notable in the PRL adenomas and carcinomas in which the region-specific antisera against vasostatin I and vasostatin II detected these fragments in the lowest percentage of tumors and/or had the weakest immunoreactivity. The CgA peptide fragment detected by CgA 176-195 (chromacin) antiserum was expressed by the highest percentage of most functional and nonfunctional benign and malignant pituitary tumors. ACTH carcinomas (n = 3) were more strongly immunoreactive compared to the ACTH adenomas. These results show that there is differential expression of CgA peptide fragments and PC1/3 among different types of pituitary tumors and that ACTH pituitary carcinomas have higher levels of immunoreactive CgA peptide fragments compared to ACTH adenomas. This study also shows the utility of tissue microarrays in the analysis of a large group of tumors with regionspecific antisera.

Cleavage of Chromogranin A N-terminal Domain by Plasmin Provides a New Mechanism for Regulating Cell Adhesion

It has been proposed that chromogranin A (CgA), a protein secreted by many normal and neoplastic neuroendocrine cells, can play a role as a positive or a negative modulator of cell adhesion. The mechanisms that regulate these extracellular functions of CgA are unknown. We show here that plasmin can regulate the anti/pro-adhesive activity of CgA by proteolytic cleavage of the N-terminal domain. Limited proteolytic processing decreased its anti-adhesive activity and induced pro-adhesive effects in fibronectin or serum-dependent fibroblast adhesion assays. Cleavage of Lys(77)-Lys(78) dibasic site in CgA(1-115) was relatively rapid and associated with an increase of pro-adhesive effect. In contrast, antibodies against the region 53-90 enhanced the anti-adhesive activity of CgA and CgA(1-115). Structure-activity relationship studies showed that the conserved region 47-64 (RILSILRHQNLLKELQDL) is critical for both pro- and anti-adhesive activity. These findings suggest that CgA might work on one hand as a negative modulator of cell adhesion and on the other hand as a precursor of positive modulators, the latter requiring proteolytic processing for activation. Given the importance of plasminogen activation in tissue invasion and remodeling, the interplay between CgA and plasmin could provide a novel mechanism for regulating fibroblast adhesion and function in neuroendocrine tumors.

Neuroendocrine differentiation in carcinoma of the breast. Tyramide signal amplification discloses chromogranin A-positive tumour cells in more breast tumours than previously realized

The aim of the study was to determine if, by means of tyramide signal amplification (TSA), the presence of chromogranin A (CgA)-positive tumour cells could be demonstrated in breast cancer cases found to be negative by conventional immunohistochemical staining. Sections from 44 cases of breast cancer (28 infiltrating ductal carcinomas, 2 lobular carcinomas, 4 ductal carcinomas in situ (DCIS), 7 lobular carcinomas in situ (LCIS), and 3 mucinous carcinomas) were stained for CgA by conventional immunohistochemical methods and by immunohistochemistry with TSA. The sections were also histologically graded and their oestrogen receptor (ER), progesterone receptor (PgR) and HER-2 oncogene status was recorded. Five of the tumours showed CgA-positive staining with the polyclonal antibody 430 with conventional methods. Thirty cases showed CgA-immunoreactive tumour cells after immunohistochemical staining with the polyclonal antibody 430 with TSA. However, eight of these also showed faint staining with the negative control antibody X0936 with TSA. One case showed immunopositivity for CgA using a monoclonal antibody without tyramide amplification and only a further two cases were positive when TSA was applied. The presence of CgA appears to be associated with a lower histological grade and may be more often found in oestrogen receptor-positive tumours.

Structure-activity relationships of chromogranin A in cell adhesion. Identification of an adhesion site for fibroblasts and smooth muscle cells

Previous studies showed that chromogranin A (CgA), a glycoprotein stored and co-released with various hormones by neuroendocrine cells and neurons, can modulate cell adhesion. We have investigated the structure-activity relationships of CgA using fibroblasts and coronary artery smooth muscle cells in adhesion assays. A recombinant CgA fragment 1-78 and a peptide 7-57 containing reduced and alkylated cysteines (Cys(17) and Cys(38)) induced cell adhesion after adsorption onto solid phases at 50-100 nm. Peptides lacking the disulfide loop region, including residues 47-68, 39-59, and 39-68, induced cell adhesion, either bound to solid phases at 200-400 nm or added to the liquid phase at 5-10 microm, whereas peptide 60-68 was inactive, suggesting that residues 47-57 are important for activity. The effect of CgA-(1-78) was blocked by anti-CgA antibodies against epitopes including residues Arg(53), His(54), and Leu(57). Substitutions of residues His(54), Gln(55), and Asn(56) with alanine decreased the cell adhesion activity of peptide 47-68. These results suggest that the region 47-57 (RILSILRHQNL) contains a cell adhesion site and that the disulfide bridge is not necessary for the proadhesive activity. The ability of soluble peptides to elicit proadhesive effects suggests an indirect mechanism. The high sequence conservation and accessibility to antibodies suggest that this region is important for the physiological role of CgA.