Targeted serum glycoproteomics for the discovery of lung cancer-associated glycosylation disorders using lectin-coupled ProteinChip arrays.

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.

Elevated levels of human alpha -defensin in tears of patients with allergic conjunctival disease complicated by corneal lesions: detection by SELDI ProteinChip system and quantification.

PURPOSE: To analyze levels of alpha -defensin in the tears of allergic patients (with/without corneal lesions) comparing the results with those of normal control subjects. METHODS: Screening of the protein profiles of the tears of allergic patients with corneal epithelial lesions and normal controls was performed by surface enhanced laser desorption/ionization (SELDI) ProteinChip array initially. ELISA was then performed to quantify the levels of alpha -defensin in the tears of allergic patients (with/without corneal epithelial lesions) and normal control patients. RESULTS: Proteins expressing significant differences between patients and controls by SELDI analysis were examined. Several peptides with molecular weights similar to alpha -defensins were found to be expressed to a greater extent in allergic patients. ELISA was performed in tears of allergic patients and control subjects to ascertain the presence and increased expression of alpha -defensins in allergic patients. Concentrations of alpha -defensins in allergic patients with corneal epithelial lesions were significantly higher than those of allergic patients without epithelial lesions or normal controls. CONCLUSIONS: Alpha-defensins were found in greater concentrations in tears of allergic patients with corneal lesions. The antimicrobial effects of alpha -defensins may play a role in the prevention of secondary infection of corneal lesions in allergic patients. SELDI ProteinChip technology is a useful and effective tool in profiling the differential expression of proteins in tears.