To screen for
glycoproteins showing aberrant sialylation patterns in sera of
cancer patients and apply such information for
biomarker identification, we performed SELDI-TOF MS analysis coupled with
lectin-coupled ProteinChip arrays (
Jacalin or SNA) using sera obtained from
lung cancer patients and control individuals. Our approach consisted of three processes (i) removal of 14 abundant
proteins in serum, (ii) enrichment of
glycoproteins with
lectin-coupled ProteinChip arrays, and (iii) SELDI-TOF MS analysis with acidic
glycoprotein-compatible matrix. We identified 41
protein peaks showing significant differences (p<0.05) in the peak levels between the
cancer and control groups using the
Jacalin- and SNA-ProteinChips. Among them, we identified loss of Neu5Ac (alpha2,6)
Gal/GalNAc structure in
apolipoprotein C-III (
apoC-III) in
cancer patients through subsequent MALDI-QIT-TOF MS/MS. Furthermore, subsequent validation experiments using an additional set of 60
lung adenocarcinoma patients and 30 normal controls demonstrated that there is a higher frequency of serum
apoC-III with loss of alpha2,6-linkage Neu5Ac residues in
lung cancer patients compared to controls. Our results have demonstrated that
lectin-coupled ProteinChip technology allows the high-throughput and specific recognition of
cancer-associated aberrant glycosylations, and implied a possibility of its applicability to studies on other diseases.