This short review deals with our investigations in
neuroendocrine tumors (NETs) with
antibodies against defined
epitopes of
chromogranins (Cgs) A and B and
secretogranins (Sgs) II and III. The immunohistochemical expression of different
epitopes of the
granin family of
proteins varies in NE cells in normal human endocrine and non-endocrine organs and in NETs, suggesting post-translational processing. In most NETs one or more
epitopes of the
granins were lacking, but variations in the expression pattern occurred both in benign and malignant NETs. A few
epitopes displayed patterns that may be valuable in differentiating between benign and malignant NET types, e.g., well-differentiated NET types expressed more CgA
epitopes than the poorly differentiated ones and C-terminal
secretoneurin visualized a cell type related to
malignancy in
pheochromocytomas. Plasma concentrations of different
epitopes of CgA and CgB varied. In patients suffering from
carcinoid tumors or endocrine pancreatic
tumors the highest concentrations were found with
epitopes from the mid-portion of CgA. For CgB the highest plasma concentrations were recorded for the
epitope 439-451. Measurements of SgII showed that patients with endocrine pancreatic
tumors had higher concentrations than patients with
carcinoid tumors or
pheochromocytomas. SgIII was not detectable in patients with NETs.