Secretagogin is a new neuroendocrine marker in the human prostate.
BACKGROUND
Neuroendocrine (NE) differentiation in prostate cancer (PCa), promoted by NE cell secreted products, appears to be associated with tumor progression, poor prognosis, and hormone-refractory disease. We recently reported secretagogin, a hexa-EF-hand Ca(2+) binding protein, as a novel NE marker in carcinoid tumors of the lung and the gastrointestinal tract. The present study analyzes the expression of secretagogin in normal and malign prostate tissue.


METHODS
We analyzed immunoreactivity for secretagogin, chromogranin A (CgA), neuron specific enolase (NSE), and synaptophysin (SYN) in consecutive sections from 87 formalin-fixed paraffin-embedded (FFPE) benign hyperplastic (n = 10) and prostate adenocarcinoma (n = 77) specimens. The intracellular distribution of secretagogin, CgA, and NSE was examined by confocal fluorescent microscopy, and we characterized secretagogin in eight samples by Western blotting.


RESULTS
Secretagogin is cytoplasmic and nuclear expressed in NE and NE differentiated cells, and to a lesser extent in epithelial cells, in the benign prostate and prostate adenocarcinoma cells. Secretagogin stained 82% (46/56) of benign and 71% (48/68) of prostate adenocarcinomas and co-localized with the NE markers CgA and NSE. The expression of secretagogin is significantly correlated to CgA (P < 0.001) and NSE (P < 0.048) in prostate adenocarcinoma and to CgA in normal epithelium (P < 0.028).


CONCLUSIONS
Secretagogin is a novel NE marker in the prostate with more extended immunoreactivity compared to the NE markers CgA, SYN, and NSE. Secretagogin is widely expressed in prostatic adenocarcinoma as opposed to adenocarcinomas in other organs.
Adolf
Katja
K
Molecular Diagnostic Laboratory, Department of Clinical Biochemistry, Center for Molecular Clinical Cancer Research (CMCC), Aarhus University Hospital, Skejby Sygehus, Brendstrupgaardsvej, Arhus, Denmark.
Wagner
Ludwig
L
Bergh
Anders
A
Stattin
Pär
P
Ottosen
Peter
P
Borre
Michael
M
Birkenkamp-Demtröder
Karin
K
Orntoft
Torben Falck
TF
Tørring
Niels
N
D000230:Adenocarcinoma / Q000378:metabolism*; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D053379:Chromogranin A / Q000096:biosynthesis; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D010751:Phosphopyruvate Hydratase / Q000096:biosynthesis; D011471:Prostatic Neoplasms / Q000378:metabolism*; D064046:Secretagogins; D018709:Statistics, Nonparametric; D016708:Synaptophysin / Q000096:biosynthesis
D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; D053379:Chromogranin A; C576556:SCGN protein, human; D064046:Secretagogins; D016708:Synaptophysin; D010751:Phosphopyruvate Hydratase