The absolute quantification of eight inter-α-trypsin inhibitor heavy chain 4 (ITIH4)-derived peptides in serum from breast cancer patients.
OBJECTIVE
Various studies exploring the potential of the low-molecular-weight serum peptidome have identified proteolytic cleavage products of inter-α-trypsin inhibitor heavy chain-4 (ITIH(4)) as potential markers for different types of cancer, presumably generated by tumor-associated exoproteases. However, further elucidation of the discriminative properties of such peptides requires specific quantitative analytical methods.


METHODS
Using a recently developed and fully validated liquid chromatography-tandem mass spectrometric method, we have compared absolute serum concentrations of eight peptides derived from ITIH(4 [658-687]) to ([667-687]) (ITIH(4)-30 to -21) between breast cancer patients (n=45) and controls (n=78). Furthermore, serum samples obtained before and after surgical removal of the tumor were analyzed (n=30).


RESULTS
The inter-individual variability in measured serum concentrations was high. Nevertheless, most peptides showed a tendency toward elevated levels in the presence of the breast cancer tumor. Significantly increased serum concentrations were observed in the breast cancer group for ITIH(4)-25 (p=0.036) and -29 (p=0.015). Intra-individual comparisons of serum obtained before and after surgery showed significantly decreased serum levels after surgery for seven of the ITIH(4)-derived peptides (p<0.02).


CONCLUSIONS
The obtained results particularly suggest potential for these ITIH(4)-derived peptides in the follow-up of breast cancer after surgery.
Utrecht University, Faculty of Science, Department of Pharmaceutical Sciences, Section of Biomedical Analysis, Division of Drug Toxicology, Utrecht, The Netherlands. Irene@vandenbroek.net
Irene
I
van den Broek
Rolf W
RW
Sparidans
Annemieke W J
AW
van Winden
Marie-Christine W
MC
Gast
Eric J
EJ
van Dulken
Jan H M
JH
Schellens
Jos H
JH
Beijnen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000510:Alpha-Globulins / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D001798:Blood Proteins / Q000032:analysis*; D001943:Breast Neoplasms / Q000097:blood*; D002853:Chromatography, Liquid / Q000379:methods; D005260:Female; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood; D010446:Peptide Fragments / Q000032:analysis*; D053491:Proteinase Inhibitory Proteins, Secretory / Q000032:analysis*; D013048:Specimen Handling; D053719:Tandem Mass Spectrometry / Q000379:methods
D000510:Alpha-Globulins; D014408:Biomarkers, Tumor; D001798:Blood Proteins; D006023:Glycoproteins; C091236:ITIH4 protein, human; D010446:Peptide Fragments; D053491:Proteinase Inhibitory Proteins, Secretory; C011877:inter-alpha-inhibitor