HILIC and ERLIC Enrichment of Glycopeptides Derived from Breast and Brain Cancer Cells

Aberrant
glycosylation has been linked to many different cancer
types. The blood–brain barrier (BBB) is a region of the brain
that regulates the entrance of ions, diseases, toxins, and so on.
However, in breast cancer metastasis, the BBB fails to prevent the
crossing of the cancer cells into the brain. Here we present a study
of identifying and quantifying the glycosylation of six breast and
brain cancer cell lines using hydrophilic interaction liquid chromatography
(HILIC) and electrostatic repulsion liquid chromatography (ERLIC)
enrichments and LC–MS/MS analysis. Qualitative and quantitative
analyses of N-linked glycosylation were performed by both enrichment
techniques for individual and complementary comparison. Potential
cancer glycopeptide biomarkers were identified and confirmed by chemometric
and statistical evaluations. A total of 497 glycopeptides were characterized,
of which 401 were common glycopeptides (80.6% overlap) identified
from both enrichment techniques. HILIC enrichment yielded 320 statistically
significant glycopeptides in 231BR relative to the other cell lines
out of 494 unique glycopeptides, and sequential HILIC-ERLIC enrichment
yielded 214 statistically significant glycopeptides in 231BR compared
with the other cell lines out of 404 unique glycopeptides. The results
provide the first comprehensive glycopeptide listing for these six
cell lines.