The current study evaluated the glycoproteomic profile of tissues from
colon cancer patients. The
lectin microarray was first performed to compare the
glycoprotein profiles between
colon cancer and matched normal tissues. Level of
N-acetylglucosamine (GlcNAc) that Solanum tuberosum
lectin (STL) bound was found to be elevated in
colon cancer, which was verified through
lectin histochemistry. The subsequent glycoproteomic analysis based on STL enrichment of
glycoproteins followed by label-free quantitative nano liquid chromatography-mass spectrometry/mass spectrometry (nanoLC-MS/MS) analysis identified 72
proteins in high confidence. Among these
proteins, 17 were exclusively detected in
cancer tissues, and 14 were significantly upregulated in
tumor tissues.
Annexin A1 and HSP90β were chosen for further investigation by immunoprecipitation coupled with
lectin blots, western blots and tissue microarrays. Both
Annexin A1 and HSP90β were GlcNAcylated, and their
protein expressions were elevated in
colon cancer, compared to normal tissues. Moreover, specific changes of GlcNAc abundances in
Annexin A1 and HSP90β suggested that
tumor-specific
glycan patterns could serve as candidate
biomarkers of
colon cancer for distinguishing
cancer patients from healthy individuals.