Glycans and glycoproteins as specific biomarkers for cancer

Abstract

Protein glycosylation and other post-translational modifications are involved in potentially all aspects of human growth and development. Defective glycosylation has adverse effects on human physiological conditions and accompanies many chronic and infectious diseases. Altered glycosylation can occur at the onset and/or during tumor progression. Identifying these changes at early disease stages may aid in making decisions regarding treatments, as early intervention can greatly enhance survival. This review highlights some of the efforts being made to identify N- and O-glycosylation profile shifts in cancer using mass spectrometry. The analysis of single or panels of potential glycoprotein cancer markers are covered. Other emerging technologies such as global glycan release and site-specific glycosylation analysis and quantitation are also discussed. Graphical Abstract Steps involved in the biomarker discovery.

Keywords: Cancer; Disease biomarker; Glycomics; Glycoproteomics; Mass spectrometry; Site-specific glycosylation.

Figure 1

ROC curve analyses of significantly changed proteins detected by ELISA. (a) ROC curve for differentiating stage III ovarian cancer from normal healthy controls; (b) ROC curve for differentiating stage III ovarian cancer from benign diseases; (c) ROC curve for distinguishing stage I/II ovarian cancer from normal healthy controls. Reprinted from ref. . Copyright © 2012, American Chemical Society.

Figure 2

Representative MALDI FT-ICR mass spectra of A, mock surgery control and B, tumor-transplanted mouse sera at different points. m/z 1000 –2000 region of 10% acetonitrile fraction taken in the positive ion mode is shown. C, Change in intensities from MALDI FT-ICR MS of high-mannose N-linked glycans in sera of an intact control mouse, mock surgery control mouse, and a tumor-transplanted mouse during breast cancer progression. All values relative to Week 0 intensity. Error bars are expressed as standard error of the mean (S.E.) from three spectral scans per mouse sample. Symbol representations of glycans: N-acetylglucosamine, blue square; mannose, green circle; glucose, blue circle. Reprinted from ref. . Copyright © 2011, by the American Society for Biochemistry and Molecular Biology.

Figure 3

The general procedure for the released glycan analysis.

Figure 4

Human serum “glycan wheel” based on the relative abundances averaged from nine individual sera. Reprinted with permission from Ting Song, Danielle Aldredge, Carlito B. Lebrilla. Ref. . Copyright © 2015, American Chemical Society

Figure 5

The glycoprotein and glycopeptide analysis procedure

Figure 6

Differential analysis of peptide and glycopeptide variables from immunoglobulins in EOC. Closed dots indicate significantly different abundance levels between EOC cases and healthy controls, while open dots indicate no significance was achieved at the false discovery rate (FDR) < 0.05. Red dots indicate increased levels in EOC cases compared with controls, while blue dots indicate decreased levels in EOC compared with controls. Reprinted with permission from ref. . L. Renee Ruhaak, Kyoungmi Kim, Carol Stroble, Sandra L. Taylor, Qiuting Hong, Suzanne Miyamoto, Carlito B. Lebrilla, and Gary Leiserowitz J. Proteome Res., 2016, 15, 1002–1010. Copyright © 2016, American Chemical Society.