IsoTopics™ – November 2015 Share

Investigations into the regulation of the N-linked glycome by cancer and disease demands rigorous quantitative methods afforded by stable isotope labeling and identification given by the specificity of mass spectrometry. N-linked glycans present challenges to MS because of the complexity of their structures (MS/MS or MSn required), hydrophilicity, and low abundance. The Individuality Normalization when Labeling with Glycan Hydrazide Tags (INLIGHT^®) strategy removes the burden of pre-enrichment, enhances ESI sensitivity, and allows accurate relative quantification. Applied to ovarian cancer research, these advantages of INLIGHT^® facilitated the observation of low-abundant glycans, quantitative determination of highly significantly regulated compositions, and revealed new trends in glycan expression with cancer stage. 

---

Abstract

An early-stage, population-wide biomarker for ovarian cancer (OVC) is essential to reverse its high mortality rate. Aberrant glycosylation by OVC has been reported, but studies have yet to identify an N-glycan with sufficiently high specificity. We curated a human biorepository of 82 case-control plasma samples, with 27%, 12%, 46%, and 15% falling across stages I-IV, respectively. For relative quantitation, glycans were analyzed by the individuality normalization when labeling with glycan hydrazide tags (INLIGHT) strategy for enhanced electrospray ionization, MS/MS analysis. Sixty-three glycan cancer burden ratios (GBRs), defined as the log10 ratio of the case-control extracted ion chromatogram abundances, were calculated above the limit of detection. The final GBR models, built using stepwise forward regression, included three significant terms: OVC stage, normalized mean GBR, and tag chemical purity; glycan class, fucosylation, or sialylation were not significant variables. After Bonferroni correction, seven N-glycans were identified as significant (p < 0.05), and after false discovery rate correction, an additional four glycans were determined to be significant (p < 0.05), with one borderline (p = 0.05). For all N-glycans, the vectors of the effects from stages II-IV were sequentially reversed, suggesting potential biological changes in OVC morphology or in host response.

 

Click here to gain access to the full article

 

Hecht, Elizabeth S.; Scholl, Elizabeth H.; Walker, S. Hunter; Taylor, Amber D.; Cliby, William A.; Motsinger-Reif, Alison A.; Muddiman, David C. 2015. Relative Quantification and Higher-Order Modeling of the Plasma Glycan Cancer Burden Ratio in Ovarian Cancer Case-Control Samples. J Proteome Res, 14(10), 4394-4401.

 

---

Related Products:

Inlight Glycan Tagging Kits -  Catalog No. GTK-1000