Sensitive liquid chromatography/tandem mass spectrometry assay for absolute quantification of ITIH4-derived putative biomarker peptides in clinical serum samples.
To explore the potential of peptide fragments derived from inter-alpha-trypsin inhibitor heavy chain-4 (ITIH(4)) as serum markers for different cancer types, sensitive and specific analytical assays are required. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) would be suitable; however, a previously developed method for quantification of eight ITIH(4) fragments (ITIH(4)-21, -22, -25, -26, -27, -28, -29 and -30) was found to be insensitive for clinical use. A more sensitive LC/MS/MS assay has now been developed and validated, which was further optimized to facilitate analyses of large sets of clinical serum samples. Benefits compared to the previous method include reduction of sample volume (100 microL), omission of protein precipitation and evaporation and transferring solid-phase extraction (SPE) to a 96-well format. Chromatographic separation on an XBridge BEH300 C(18) column, using a water/methanol gradient containing acetic acid, was coupled to triple quadrupole mass spectrometric detection, applying heated electrospray ionization. Method validation revealed deviations from nominal concentrations below 10.1% and intra- and inter-assay precisions below 17.4 and 20.0%, respectively, at the lower limit of quantification (LLOQ) for all peptides. The reported changes resulted in more rapid and efficient analyses and reduced LLOQs for the six less abundant peptides (1.2; 1.0; 1.2; 2.0; 2.0 and 2.0 ng/mL vs. 2.1; 2.0; 2.5; 2.6; 2.2 and 2.4 ng/mL for ITIH(4)-21, -22, -25, -27, -28 and -29, respectively). The method has shown its applicability by quantifying all peptides in appropriate concentration ranges in serum from healthy volunteers and application to clinical samples from breast cancer patients.
Utrecht University, Faculty of Science, Department of Pharmaceutical Sciences, Section of Biomedical Analysis, Division of Drug Toxicology, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands. I.vandenBroek@uu.nl
Irene
I
van den Broek
Rolf W
RW
Sparidans
Jan H M
JH
Schellens
Jos H
JH
Beijnen
D000595:Amino Acid Sequence; D000818:Animals; D014408:Biomarkers, Tumor / Q000097:blood / Q000737:chemistry; D001798:Blood Proteins / Q000737:chemistry; D001943:Breast Neoplasms / Q000378:metabolism; D002417:Cattle; D002853:Chromatography, Liquid / Q000379:methods*; D005260:Female; D006023:Glycoproteins / Q000097:blood* / Q000737:chemistry; D006801:Humans; D016018:Least-Squares Analysis; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000097:blood* / Q000737:chemistry; D055550:Protein Stability; D053491:Proteinase Inhibitory Proteins, Secretory / Q000097:blood* / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction; D053719:Tandem Mass Spectrometry / Q000379:methods*
D014408:Biomarkers, Tumor; D001798:Blood Proteins; D006023:Glycoproteins; C091236:ITIH4 protein, human; D010446:Peptide Fragments; D053491:Proteinase Inhibitory Proteins, Secretory