Triple SILAC glycoproteomic analysis of NSCLC cell lines

Protein glycosylation plays a fundamental role in a multitude of biological processes, and the associated aberrant expression of glycoproteins in cancer has made them attractive targets as biomarkers and therapeutic targets. In this study, we examined differentially expressed glycoproteins in cell lines derived from three different states of lung tumorigenesis: an immortalized bronchial epithelial cell (HBE) line, a non-small cell lung cancer (NSCLC) cell line harboring an activation KRAS mutation and a NSCLC cell line harboring an EGFR activation deletion. Mutations in KRAS and EGFR are two common, distinct, non-overlapping genomic alterations in NSCLC. Using a Triple SILAC proteomic quantification strategy paired with hydrazide chemistry N-linked glycopeptide enrichment, we identified 118 quantifiable glycopeptides in the 3 cell lines derived from 82 glycoproteins. Proteomic profiling revealed that 27 (24%) of the glycopeptides overexpressed in both of the NSCLC cell lines with 6 of the glycopeptides overexpressed only in the EGFR mutant cells and 19 of the glycopeptides overexpressed only in the KRAS mutant cells.