LC-MS/MS Quantification of Zn-α2 Glycoprotein: A Potential Serum Biomarker for Prostate Cancer
- 1 April 2007
- journal article
- Published by Oxford University Press (OUP) in Clinical Chemistry
- Vol. 53 (4), 673-678
- https://doi.org/10.1373/clinchem.2006.079681
Abstract
Background: Zn-α2 glycoprotein (ZAG) is a relatively abundant glycoprotein that has potential as a biomarker for prostate cancer. We present a high-flow liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for measuring serum ZAG concentrations by proteolytic cleavage of the protein and quantification of a unique peptide. Methods: We selected the ZAG tryptic peptide 147EIPAWVPEDPAAQITK162 as the intact protein for quantification and used a stable isotope-labeled synthetic peptide with this sequence as an internal standard. Standards using recombinant ZAG in bovine serum albumin, 50 g/L, and a pilot series of patient sera were denatured, reduced, alkylated, and digested with trypsin. The concentration of ZAG was calculated from a dose–response curve of the ratio of the relative abundance of the ZAG tryptic peptide to internal standard. Results: The limit of detection for ZAG in serum was 0.08 mg/L, and the limit of quantification was 0.32 mg/L with a linear dynamic range of 0.32 to 10.2 mg/L. Replicate digests from pooled sera run during a period of 3 consecutive days showed intraassay imprecision (CV) of 5.0% to 6.3% and interassay imprecision of 4.4% to 5.9%. Mean (SD) ZAG was higher in 25 men with prostate cancer [7.59 (2.45) mg/L] than in 20 men with nonmalignant prostate disease [6.21 (1.65) mg/L, P = 0.037] and 6 healthy men [3.65 (0.71) mg/L, P = 0.0007]. Conclusions: This LC-MS/MS assay is reproducible and can be used to evaluate the clinical utility of ZAG as a cancer biomarker.Keywords
This publication has 14 references indexed in Scilit:
- Stage-dependent increase of orosomucoid and zinc-alpha2-glycoprotein in urinary bladder cancerProteomics, 2005
- Protein expression profiling of CLL B cells using replicate off-line strong cation exchange chromatography and LC–MS/MSJournal of Chromatography B, 2005
- The role of glucocorticoids in the induction of zinc-α2-glycoprotein expression in adipose tissue in cancer cachexiaBritish Journal of Cancer, 2005
- Crystallographic studies of ligand binding by Zn-α2-glycoproteinJournal of Structural Biology, 2004
- Zinc-α2-glycoprotein, a lipid mobilizing factor, is expressed in adipocytes and is up-regulated in mice with cancer cachexiaProceedings of the National Academy of Sciences of the United States of America, 2004
- Peptide mapping of proteins in cerebrospinal fluid utilizing a rapid preparative two-dimensional electrophoretic procedure and matrix-assisted laser desorption/ionization mass spectrometryBiochimica et Biophysica Acta (BBA) - General Subjects, 1999
- Crystal Structure of Human ZAG, a Fat-Depleting Factor Related to MHC MoleculesScience, 1999
- Immunohistochemical localization of Zn-alpha 2-glycoprotein in normal human tissues.Journal of Histochemistry & Cytochemistry, 1991
- Sweat protein components tested by SDS-polyacrylamide gel electrophoresis followed by immunoblotting.The Tohoku Journal of Experimental Medicine, 1990
- Renal handling of Zn-alpha2-glycoprotein as compared with that of albumin and the retinol-binding protein.JCI Insight, 1976